Quicksand Sucks: Crocodile's Desert Girasole basically left Luffy sinking into a large pool of quicksand with seemingly no way of getting out. It's a good thing Miss All-Sunday was around at the time to help.
There's also Caribou who is basically a living swamp that everything sinks into. Said swamp has infinite space to hold things.
Rank Up: Captain Smoker gets promoted by the Marines to Commodore. Commodore Smoker is not too happy about his promotion as he feels he didn't deserve it, but he does use his new leverage to operate wherever he wants.
He has now been promoted to vice-admiral. Tashigi was promoted five times from Ensign to Captain.
Speaking of the Marines, Coby went from Chore Boy to Master Chief Petty Officer, after some intense Training from Hell under Garp. After the Time Skip, he's a captain, the same rank as Tashigi, which means he ranked up even faster than her.
Rapid Aging: In chapter 650, Hody and his gang end up turning into old men. Apparently it's one of the side effects of all of those pills they took. Funny and sad at the same time.
Rasputinian Death: WHITEBEARD. What he went through simply has to be seen to be believed. Even the Narrator comments on it. Full list: 152 Gunshots, 267 Sword wounds (including one all the way through his chest), 46 cannon balls, and two counts of being impaled by LAVA. And this is from a man who is already very old and on freaking dialysis. Wow.
Might I add that in the manga, HALF HIS FACE IS MELTED OFF!AND HE DIES. STANDING. UP.
Razor Wind: Many of the attacks in the series, namely Cipher Pol 9's "Rankyaku" and Zoro's "Poundo Hou" and "Tatsumaki" techniques. Mr. 1 is a pretty blatant example, since he can slice things up just by waving his hands. We don't even see any wind.
Reality Ensues: Yes, even a series as wacky as One Piece can be surprisingly astute and thoughtful when it comes to economics, politics and problems that cannot be solved by fists and super-powers. And ironically, such observations are often made by Luffy and Usopp, much to the surprise of their crew.
For example, most pirating adventures conveniently skirt the issue of just how our heroes will get to spend their ill-gotten mountain of glittering gold and jewels, and automatically Time Skip to them becoming filthy rich kings-and-queens. Not so One Piece, as Luffy discuss with Usopp and Nami on how to pay for repairing the Going Merry with their loot of priceless Shandoran gold, which might as well as be worthless-scrap if they don't take a trip to the local pawnbroker first.
Luffy: Can't we just go straight the shipyard? Ussop: We can't just carry all this gold with us; makes me bloody nervous. Luffy: But the value won't change even if we don't exchange it for cash, right? Ussop: Yeah, but carrying around all this gold will attract a LOT of unwanted attention; what if bad guys try to rob us because of it? Luffy: But we are the bad guys. Nami: In other words, once we change this gold for bank-notes, even we can carry and spend it without any trouble!
Enel's and Nami's lightning abilities are treated more realistically than most of the logias. Sure, the people hit by them don't die like they would in real life, but even one electric shock is enough to drop the likes of Sanji, Kalifa, and everybody else attacked by Enel or Nami without any problems. Even Zoro could only take two shocks from Enel.
Real Men Wear Pink: Sanji has worn pink, and it is Chopper's identifying color. Donquixote Doflamingo wears a pink feathery overcoat, and has proven himself to be pretty badass at the Battle of Marineford. And of course, the manliest of men, Bon Clay.
Arlong is quite fond of giving these to humans to show why Fishmen are superior. Luffy counters by inverting the trope, giving a Reason I Suck Speech stating everything his crew can do that he can't, then adding that the one thing he can do is kick Arlong's ass.
Cavendish unleashes one on the tournament spectators who were jeering and screaming for Rebecca's death. He calls them out on their cowardice as it is easy to scream for death from the safety of a spectator and if they really had a desire to see Rebecca dead, they should have joined the tournament.
Robin was a criminal who asked Luffy for a place on the crew instead of the other way around (Luffy's usual MO). At first it appeared they were just the latest in a long string of criminals she'd associated herself with, but it turns out that she'd been on the lam for 20 years and this was the first time she felt like she had a "home".
Shiliew is bored to death with Impel Down prison and, when the Blackbeard Pirates broke in, he asked them to join their crew, and they let him in.
Luffy specifically recruited Nami to free her from Arlong's rule. That, and he needed a navigator.
Red Baron: Basically everyone who isn't a civilian or a total weakling.
Red Oni, Blue Oni: Taken to a pretty much literal sense with Oars and Nightmare Luffy.
Also Dorry and Broggy, who were called the Red and Blue Ogres.
Sanji and Zoro have a weird mix of this, with Sanji normally being Red, passionate and romantic, and Zoro being cold and deadpan, when they get into fights however Zoro gets his smile on and Sanji quits acting like a fool.
We also have Luffy and Zoro, one being hot-headed, headstrong and wild, with the other being calm, serious and controlled (most of the time).
Orange-haired and red-eyed Nami who gets easily annoyed at the stupidity of the crew, versus black for Robin who laughs at their antics and has only once ever had a Demon Head (at an enemy).
On the Marine's side, there's Garp and Sengoku, with Garp as the Red Oni and Sengoku as the Blue Oni. This is demonstrated further in the anime version of Episode 0, where Garp wears a red tie and Sengoku wears a blue tie.
Red Shirt Army: All marines (besides those few with names and/or backstories) are just one big version of this trope.
To clarify: got a crazy theory on what'll come up? Oda will most likely top it in the most out-of-field way possible.
The Japanese language makes the pun, the term for the Phone/Transponder snails is Dendenmushi which means snail normally. Den in Japanese can mean Electric and Communication, and Mushi is bug, so the word for snail becomes Electric Communication Bug. Compare with the word for Telephone, Denwa, which means Electric Conversation.
Rescue Arc: The Enies Lobby Arc revolves around the Straw Hats trying to save Robin from the clutches of the World Government, who plan on harvesting her knowledge of and then killing her for reading illegal inscriptions.
The Impel Down arc begins with Luffy's attempt to rescue his brother Ace from the most fearsome prison in the world.
After failing to spring Ace, Luffy decides to bust out of Impel Down (a prison considered impregnable), with an army of over 200 rowdy criminals including two Revolutionaries, two Warlords, and Buggy, and head to Marine Headquarters to join the Final Battle and attempt to stop Ace's execution.
Retcon: The Armament Haki turning the users' skin or weapons black and shiny was added in after the Timeskip with no explanation given for it's lack of existence before the Timeskip; before, it was simply invisible. Justified however; with so much importance placed on Haki usage in the New World, there needed to be a way to more clearly distinguish when it was being used or not.
Retired Badass: Red Leg Zeff, Silvers Rayleigh, Shakky, and Doctor Kureha.
Revealing Cover Up: When the denizens of Punk Hazard's attempt to fool Smoker into leaving the island backfires because he's familiar with the island's history.
Revenge by Proxy: One pirate in the Dressrosa Tournament is after Luffy because of what Garp did to this man and his family years ago.
Reverse Mole: Nico Robin. Also possibly Bartholomew Kuma as a mole in the World Government for Dragon, though we didn't get more than vague hints regarding this.
As of the latest chapter, Kuma is revealed to really be a mole for Dragon and that this was his reason for saving the Straw Hats back at the Sabaody Archipelago.
The Revolution Will Not Be Vilified: Dragon is leading a revolutionary war against the tyrannical, slave owning, massacre happy, conspiracy loving World Government. Fisher Tiger rescued slaves and lead an attack against the incredibly corrupt and decadent nobility. Other revolutionaries are shown freeing Robin from a work camp. The worst thing anyone to do with the Revolution has been shown doing is Ivankov's Gender Bender antics. Now Oda may turn this around when we learn more about the Revolution but so far they've been portrayed as entirely heroic.
Though if you pay attention one of the Revolutionaries seems to have just shot someone execution-style in the coverstory, usually something that isn't seen as very humane, but it remains to be seen what the overall attitude of the movement is.
Ridiculously Fast Construction: At one point during Thriller Bark, Franky, Usopp, Sanji and Zoro come across a place that they can't jump over. Usopp, Sanji and Zoro turn around and in about five seconds, they turn back around and see that Franky just built a bridge. Later on, Nami runs across it and comments how quickly yet well made it looks.
Rightful King Returns: Wapol came back to his kingdom and got promptly sent flying into the sky by Luffy. Also, King Nefertari returned after Luffy kicked Crocodile's ass and peace returned to Alabasta.
Donquixote Doflamingo retook control of his family kingdom after eight centuries. Like in the case of Wapol, the usually idealistic trope is twisted in his hands, him being evil and those having ruled in his stead good and fair people.
Queen Otohime of Fishman Island makes time in her day to be a mother of 4, schoolteacher, rescue worker and activist.
Ricky/King Riku secretly participated in the Corrida tournament to win the Mera Mera Fruit to overthrow Doflamingo. Likewise his granddaughter Rebecca is doing the same and manages to win the D round to advance to the finals. And then there is Violet/Viola, Riku's daughter who is a Reverse Mole and is helping the Straw Hats against Doflamingo.
Rubber Man: Monkey D. Luffy himself. A particularly literal example, in that he can't truly shapeshift like some Rubber Men, but he can stretch any part of his body to ridiculous lengths, is extremely resistant to electrical and blunt-force attacks, and uses rubber's natural "snap-back" in most of his attacks.
Rugged Scar: Invoked by Luffy, who gave himself a scar under his eye in honor of his hero Shanks. Shanks himself has a claw mark scar over his eye from his fight with Blackbeard.
Rule 63: While a normal rule of the internet, this one bears special notice in that ever since the introduction of Ivankov's ability to pull a Gender Bender at-will and Oda's illustrated response◊ to a fan question as to what it would look like if applied to the main cast, there has been an absolute deluge of Gender Flipped art on the internet, and Oda has only himself to blame.
Rule of Cool: Do most of the Devil Fruit powers make sense or follow any sort of physics? No. Are they cool? Yes. On a more wide range, the series itself seems to run on this at times. And it is awesome.
Rule of Funny: Tons of things. For one, it's the only reason that Chopper and Brook always jump in to save Luffy when he falls overboard, despite the fact that not only do they share his Super Drowning Skills, one was never able to swim in the first place and the other has had them longer than the other two combined.
Running Gagged: Usopp's lies. This slowly started fading out due to his Character Development. In the beginning, Usopp would lie often and sometimes for no good reason. Now he lies rarely and usually has a battle plan whenever he does.
Until you realized that his lies became a Self Fullfilling Prophecy. For example, he lies about fighting a dragon(came true in Punk Hazard arc), he also lies about fighting a three-headed dog(Gecko Moria arc), and he lies about a giant goldfish(shows up at the end of the Little Garden arc).
Sarcastic Confession: In the G8 filler, when a captured Zoro was being interrogated by the Marines how he snuck into the fortress. Zoro tells them in a bored voice that he fell from the sky.
Scare The Dog: One of the first memorable moments is Shanks scaring off a giant eel to cement how much of badass he is. Later Luffy does it similarly with a bison. Much later, it's revealed what they did was a form of Haki that only a select few are capable of doing.
Scary Shiny Glasses: Captain Kuro and Admiral Kizaru. Though with the latter he's very cheery. Unfortunately almost every pirate is afraid of this guy and that's before having some knowledge what he can actually do.
Kuma also manages to pull this off in the anime, despite the fact that he's technically not wearing glasses.
Schizo Tech: In a world with relatively old-fashioned technology, we have things like cyborgs that are capable of firing laser beams from their mouths, though this is Hand Waved by saying that the mind behind said laser-firing cyborgs is several centuries ahead of its time.
Franky was sent by Kuma to a futuristic winter island where the mind in question was born.
They also apparently have flat-screen TVs and stereo speakers. Seriously.
Justifiable - most of the islands are separated by wild weather, sea kings and wonky magnetic fields. One region's advances take a long time to spread, except when it is beneficial for the World Government or Marines who can bypass those obstacles.
Scissors Cuts Rock: Luffy, being a rubber man, is immune to Eneru's electricity-based powers. However, Eneru finds ways to hurt Luffy anyway by applying electricity indirectly, culminating in his tossing Luffy overboard with a gigantic gold sphere attached to his wrist serving as an anchor. Luffy defeats Eneru as soon as he gets out of the mess, but Eneru did turn what should've been a Curb-Stomp Battle into one where he had the edge.
Screw the Rules, I'm Doing What's Right: Jinbe after Luffy's fight with Hody, as he gives Luffy a blood transfusion despite Fishman Island's law that Fishmen are not allowed to give blood to humans. Jinbe justifies this by noting that he's pirate, and acts outside the law anyway. However, it's made clear that after the events of the arc thus far, none of the Fishmen are really interested in enforcing that law anymore, least of all against the guy most responsible for saving Fishman Island and everyone on it.
Senseless Sacrifice: A nonlethal comedic variant. There's been at least one instance where Luffy fell into the water, and Chopper, and later Brook dove in to save him, forgetting that they are also Fruit Eaters, and can't swim either. Zoro saved them each time, though.
Along with how much damage he takes before managing to pull off said finishing move.
Shadow Walker: Variation. Gecko Moria can detach his shadow which can move freely far away from him. He can then teleport to switch places with it. This is used to reach great distances safely as well as acting as decoy.
Shapeshifter Guilt Trip: Subverted and then played straight as Sanji has no problem kicking Mr. 2 around when he looks like Usopp, but the minute he transforms into Nami...
Shapeshifting: All Zoan fruits do this, allowing the user to shift between their natural form, a particular animal form, and a hybrid of the two. Chopper is notable in that his Rumble Ball temporarily grants him further variations. Some Paramecia fruits grant similar powers, most notably Mr. 2 Bon Clay's, which lets him transform into other people.
Shark Man: Any shark-type fishman, Arlong and Hody being prime examples.
Shonen Hair: Notably absent. While Luffy has one it looks pretty normal compared to other shonen hairs.
Shooting Superman: You would think that by this point, everyone would know that trying to hurt Luffy with a bullet would be almost suicidal. Especially since the bullet might come back and shoot you instead.
And now after the Time Skip he can absorb enemies' attack and return it with twice the power.
Shout-Out: There's a Shout-Out to the second Terminator film in episode 443 where Crocodile takes a headshot and the resulting hole and camera angle is identical to the one in the scene where the T-1000 is headshotted during the film's climax.
Saint Jalmack the Celestial Dragon's cube-shaped air helmet looks a lot like the ones at the end of WALL•E.
The maw of Bowin Archipelago looks a lot like Unicron.
In chapter 592 of the manga, Brook is referred to as Master Satan.
Sanji's fight with Scarlet in Movie 10 is a very blatant one to King Kong: A huge ape (Scarlet) kidnapping a beautiful young woman (Robin), and bringing her to the top of a tower. It ends, however, with Scarlet being knocked down through the tower instead of off of it.
A possible shout out is Brook opening his afro/skull as though it is on a hinge and storing items (namely his Tone Dial) inside, in a similar fashion to Bobobo-bo Bo-bobo.
In episode 467, The art shift made to represent extreme hot blood and Luffy's large spinning fist are strangely familiar...
Additionally, one of the Kuja tribeswomen looks a lot like a brown-haired Yoko. Since the director for that episode had worked on Gurren Lagann, it's probably not a coincidence.
This is farfetched but Diamond Jozu might be a reference to the old American folk song Diamond Joe, with his "diamond studded jaw".
In chapter 619, Neptune pulls off an attack which, down to the arm movements and the effect, resembles a Kamehameha wave.
Nearly 600 chapters after his meeting with Luffy, Gaimon reappears in a cover page with a new friend. Together, they are Gaimon and Sarfunkel.
'Iron Mask' Duval, leader of a group of Flying Fish Bikers, wields a spear-gun shotgun and complains about the painful scar on his back while doggedly pursuing 'the man who cast him into hell'... a subtle reference to Jagi of Fist of the North Star, perhaps? To the writer's credit, however, the words 'You are already dead' were never uttered. That must have been tempting.
However, considering that the cryptogram's history is only tracable back to 1923, there is no hard evidence that the message is original, or that such a message existed in the first place, or that Levasseur ever buried treasure. Spoiler indeed.
In episode 455, Soran recieves a chocolate bar that looks a suspicious lot like a Wonka Bar.
Corazon, Doflamingo's younger brother, is actually named Rosinante, a call back to the name of Don Quixote's "steed" Rocinante.
Shower Scene: Nami has had these during filler and in Thriller Bark. She even develops a technique for it over the time skip.
Shown Their Work: Oda frequently incorporates real life phenomena into his work is usually pretty close to the original event or story, minus some typical One Piece shonen exaggeration. Examples include the Going Merry's Klabautermann spirit and the "Brocken Spectre" as the source of the giant shadows seen early in the Skypeia arc. Even something as mundane as the Marines' saluting palm-inward is derived from real naval practices which were done to avoid showing tar-stained hands to superiors.
Shut Up, Hannibal!: At the turning point of the CP9 saga, when the Straw Hat pirates face of with the leader of a secret government agency.
Spandam: Look at that symbol, pirates! *point to the flag of the world government* That mark represents the unity of over 170 nations! This is the world! Do you understand how insignificant you are to stand against us!!? Luffy: I understand very well. Sogeking, shoot that flag.
Signature Laugh: Several major and not so major characters in the series have a unique laugh.
Signature Team Transport: Most crews have one, each having a particular design for their ship. And then, there's Going Merry and Thousand Sunny for the Straw Hats.
Significant Birth Date: Luffy's birthday is on Children's Day (May 5), Usopp's is April Fool's Day, and Chopper's is Christmas Eve. Sanji's, Franky's, and Brook's are word puns. Zoro's birthday is also a word pun, but it falls on Armistice Day.
Specifically invoked for most characters, as birthdays are usually determined by a fan suggesting one to Oda with logic based on this trope, with Oda making them canon.
Invoked Trope: This is forced because Zoro is on a train and T-bone is on the tracks, they only have time for one slash and both realize it. Except...Zoro's attack is a feint, leaving T-bone's flank open. Clever girl...
It's either Subverted or taken to the next level with Brook vs Himself (His fighting style in a super powerful zombie body). Both use their ultimate technique, which consists of walking toward the other with their sword out. In the end, it's so fast (or so special) that it becomes aZero stroke battle. The loser simply falls down.
A Sinister Clue: Inverted with the main cast, they all have something special on their left side, like Usopp's armband, Chopper's antler plate, Nami's tats, Zoro's earrings, Luffy's scar, Sanji's covered eye; in fact, there's a list somewhere that contains all the important left things.
Sinister Surveillance: Eneru during his time as God literally turned Skypeia into Big Brother in Heaven by using his Devil Fruit abilities to increase the strength of his Haki/Mantra to hear the conversations of everyone on the island. Intruders, "blasphemers" and those who his men hadn't eliminated yet were punished by him with a column of lightning from above.
Sins of Our Fathers: One of the major themes of the series is whether or not an innocent child should bear the sins of their parents if they are criminals. The main reason why Ace's execution (and eventually Luffy's death) was such a high priority to the Marines is because of their biological heritage. Both their fathers were/are notorious, world-renowned criminals: "The Pirate King" Gold Roger and "The Revolutionary" Monkey D. Dragon respectively. Thus, the first and greatest crime that both brothers committed (at least in the eyes of the world), was the sin of being born into this world. Even if they had never become pirates, they would have never been allowed into the Marines and would never have a chance at a normal life — for the world itself would never have allowed them to live. This was the main source of Ace's angst, and in his dying moments, he admitted to Luffy that all he ever wanted to know is whether or not he deserved to be born. Most tellingly, Oda has stated that one of the themes of One Piece is that heritage doesn't matter and family is who you choose.
The Smurfette Principle: As could be expected from a Shōnen series, most significant groups and teams only count one female among them. The Straw Hats used to walk that way until Vivi joined. Once she left, they went Smurfette again for the span of a half a chapter until Robin joined them for good as an Affirmative Action Girl.
So Last Season: After the Time Skip, the Marines get a taste of this when they see two Pacifistas easily defeated by Luffy, Zoro, and Sanji. The Mecha-Mooks aren't going to cut it against the Straw Hats anymore.
It has to be noted that Sentomaru mentioned that the two PX units that Luffy, Zoro and Sanji defeated were of the same model as the ones that previously attacked the Straw Hats on Sabaody. This implies that there are newer, stronger Pacifista models that even the Monster Trio might have trouble against. However, this in no way detracts from the pure awesomeness of the two PX units being OHKO'd after only one of them almost completely defeating the entire Straw Hat Pirates two years prior.
Sorting Algorithm of Evil: Justified in that the Grand Line acts as a natural selecting factor: the farther you go, the more powerful enemies you're likely to encounter, because only the strong get that far.
But subverted by Mihawk, Aokiji, and Kuma, who wipe the floor with their chosen opponents and don't kill them only because they have ulterior motives. Also subverted by Crocodile who, while beaten by Luffy in his arc, is still able to fight with some of the strongest characters introduced in the series and hold his own.
To be completely fair, Crocodile's Logia ability has a very huge weakness - without which Luffy would not have been able to win (as he did not have any idea what Haki was at that point in time). It may be safe to assume that not a lot of people know about this weakness, thus making Sir Crocodile an extremely dangerous foe for many.
Also subverted in the opposite fashion by the Flying Fish Riders, who are far weaker than the Straw Hats' previous opponents, and easily defeated.
Subtly averted with the henchman of Gecko Moria in the Thriller Bark arc, as they go down much easier than the previous arc's villains, CP9.
No mention of the Sabaody Archipelago arc? First the Straw Hats run into a Pacifista, a cyborg duplicate of the Warlord of the Sea Bartholomew Kuma, that they defeat with great effort. They are then immediately confronted by another Pacifista, Admiral Kizaru and Sentomaru. The Straw Hats are utterly annihilated and only saved from being killed by the timely intervention of the real Kuma.
It's also subverted by the Fishman Island Arc. Hody was a pushover compared to basically anyone Luffy faced during the Summit War Saga.
Speaks Fluent Animal: Chopper, of course. Due to him eating the hito-hito fruit, he can translate them for humans as well.
Most notably are Luffy to Ruffy (German) and Zoro to Zolo (English).
To be fair, though, Zoro's name change was justified by the fact that the owners of Zorro threatened to sue.
Not to mention Enel/Eneru. (the latter is official)
And Brook/Brooke. (the former is official)
Is it Oz, Odz or Oars?
Wordof God says "Oars", as his descendant's ship's sail carries the name.
One of Whitebeard's subordinate Captains (the one that shanked Whitebeard), has variously been referred to as Squado, Squad, Squardo, Spardo and many other names besides. (English manga uses Squard)
There's also Dracule/Juraquille (former is correct), Jozu/Joz/Jose/Jaws(first one, if going by the English manga), Margaret/Marguerite, and Jinbei/Jimbei.(Actually confirmed as Jinbe in a Data Book, though FUNimation and Viz use Jimbei)
And some fans disagree on whether it's Blueno or Bruno. He has a sign in his tavern in Water 7 which reads "BLEUNO", which is possible, since "bleu" is French for "blue", and in Japanese both would be pronounced like "blue" in English.
Some fans also think it should be spelled Iceburg or Iceburgh, due to it being written as "ICEBURG" in the manga at one point and apparently being a pun on Pittsburgh. However, it's also written as "ICEBARG" in the anime at one point, which means that "Iceburg" was most likely a misspelling on Oda's part (whose English is far from perfect) and that it is actually meant to be Iceberg.
However, the best example has to be the spelling of Mr 2.'s codename. Officially, and according to Word of God, it's "Bon Kurei", referencing the Obon festival. However, absolutely EVERYONE, even OFFICIAL SOURCES FROM JAPAN, romanise it as "Bon Clay". Apparently no one except Oda got the reference.
The currency itself. Is it beri, beli, berri, belly, or berry? It doesn't help that Oda has used more than one spelling on the actual bills.
There's also Big Mom. For a log time, people were in debate over whether or not it was Big Mom or Big Mam, and even the wiki went with the latter. However, it has since been confirmed to be Big Mom.
We now have Madame Shirly/Shyarly
Spike Shooter: Miss Doublefinger, due to eating the toge-toge no mi/Spike-Spike fruit.
Spin-Off: With the debut of the Super Strong Jump magazine (essentially Jump made for 10 and younger). Chopperman was was spun off into his own series. The series is neither written or drawn by Oda and takes place in an alternate universe where Chopper is a health teacher at a elementary school. Nami is the principal of said school, most of the students are kid characters or chibi versions of characters from the main series. Usopp is still the main villain however.
Spit Take: Luffy and Usopp order several barrels of water, not realizing that they are sitting next to Smoker and Tashigi. Once they do, they end spitting a whole bunch of water right into the Marines' faces. It is hilarious.
Spoiler Opening: While most of the openings confine themselves to just showing new characters, the fifth and sixth featured previews of upcoming scenes, while the third showcased Robin as a crew member... nearly twenty episodes before her Heel-Face Turn. Oops.
The 11th opening just goes right ahead and pretty much shows every new character and such from where the anime currently is right up to the current manga arc.
The 12th opening spoils the hell out of Impel Down and Marineford.
And shockingly, a recent flashback reveals that Ace was one when he first joined Whitebeard's crew.
Avalo Pizarro seems to be thinking of becoming one from Chapter 595.
Starting A New Life: several of the minor villains get mini-arcs showing what they've done with their lives after being defeated by Luffy.
Start of Darkness: When Fishmen first appear in the series, they seem like little more than racists who terrorize innocent humans for sport. As it turns out, they've got a damn good reason to distrust, if not outright hate, humanity for the things they've forced Fishmen to endure. Not that unrepentant murderer Arlong is going to be turned by giving him a hug or anything, but you can definitely see where his species is coming from.
Stocking Filler: Fishnets are standard issue for the transvestites of Newkama Land. According to Oda, they wear them for the same reason people climb mountains—because they're there.
Story Arc: Not counting some filler, the show entirely consists of arcs of different length. And even most filler consists of these.
Straight for the Commander: In the Alabasta Arc (specifically in the Alabasta civil war), our heroes deemed that the situation has too far gone south to be resolved in peaceful ways. Luffy then deduces that there's only one other way to solve the conflict: Beat the guy behind them all, Crocodile. His crew were initially surprised about Luffy's plan but it works in the end.
Really, this is often Luffy's strategy: Rushing in first to find the one behind the conflict (and/or the strongest of the enemy) and then beating them, often conflicting with the rest of the crew's plan.
Strange Minds Think Alike: Luffy manages to smuggle Princess Shirahoshi (with good intentions) by having her hide in her pet shark Megalo's mouth. Brook thus argues that since he only saw Luffy and Megalo leave the castle, Luffy couldn't have kidnapped her. Neptune immediately suggests that she might have hid in Megalo's mouth (all the other members of his court burst out laughing, saying that the idea's too weird).
Chapter 649 has a Call Back where Zoro argues he doesn't want to be a hero because that would mean he would have to share his beer. Earlier, Luffy had this exact same thought except with meat. Nami lampshades it.
This makes it a bit of Truth in Television since the modern day naval salute (of both the Royal Navy and US Navy) is still palm inwards. In fact, it's the palm outwards salute of the RAF and British Army that may be considered a Strange Salute since most modern armies salute with their palms downward (or inwards).
Straw Vulcan: Bellamy derides the Straw Hat crew for chasing fairy tales, and even provides a logical explanation for ships falling from the sky. However, this is meant to portray him as a villain... except he totally has a point. They ARE chasing fairy tales.
No, that would make him a rival/antagonist. What makes him a villain is that he's an asshole.
Plus, he realizes how wrong he was when he visits Sky Island himself.
Sunk Cost Fallacy: When the residents of Nami's village decide to try and remove Arlong by force, Genzo talks them down citing how long they've waited for outside help. Subverted when it is revealed that Genzo, and the rest of the villagers, were well aware of Nami's plan to buy the village from Arlong. Instead of "we've waited so long we have to keep going" its "Don't make trouble when our Plan A is almost finished."
Super Drowning Skills: Anyone who has a Devil Fruit loses the ability to swim. On top of that, they can't use their powers to get out of the water (though others can do so for them in certain cases, such as stretching Luffy's rubber body when he can't move).
Super Not-Drowning Skills: Merfolk deserve a mention as Fishmen can actually drown if their gills are covered, but most Merfolk don't have any gills and breathe in water anyway.
Superhero Speciation: There can only be one of each Devil Fruit at a time, so when a person, animal or object eats one, they are the only one with that power. When they die, a nearby fruit will turn into their Devil Fruit ready to be eaten again.
Superpower Lottery: Devil Fruits come in three types. Paramecia gives you a quirky ability. Zoan allows you to transform into an animal. Logia types grant you utter control over an element of nature, allow you to produce it in massive quantities from your body, and allow you to turn into that element to become practically invincible. Each is rarer than the next. There's also rare divisions within the three classes. Zoan for example, has Ancient Zoans and Mythical Zoans. The former is extinct animals like dinosaurs, the latter is outright fictious monsters like a phoenix. Yeah...
Super Smoke: Most Logia can do this as a rule. The heavier ones can't as easily, but generally make up for it with sheer power.
Smoker is a literal example of this.
Suspiciously Specific Denial: In a flashback in episode 8, when Shanks tries to get Buggy to join the celebration, Buggy blurts out that he didn't steal anything. (He did.)
"We didn't see anything! Especially not the zombie you're making!"
In TV Special 4, while pretending to work for Buggy, Zoro deliberately attacks Mohji and Richie to protect Vivi. Right afterwards, he says "Sorry, my hand slipped", which Cabaji calling him out on his lie.