While most of the time, Jojo's Bizarre adventure is a serious battle manga, most of the cast is completely insane. Half the fun is watching them pull out incredibly zany schemes, hurt each other in increasingly ridiculous ways, or play off each other, with their own brands of Insane Troll Logic.
Speedwagon's reaction to Jonathan and Erina sharing a tender moment. "Speedwagon withdraws coolly."
Speedwagon begs Zeppeli to teach him the Ripple power as well. Zeppeli finally capitulates and hits Speedwagon in the torso with a pinkie just like he did with Jonathan...only Speedwagon merely doubles over in pain, causing Zeppeli to wonder if he hit the wrong spot in frustration.
Made better because Jonathan never used that, and he refers to it as if it was passed down the family line.
After his Training from Hell, Joseph shows off his new abilities by challenging a mugger to stab him. When he tries to do so, he stops the blade with one finger, and then pulls out a container of mustard and squirts it all over the mugger's head. After about a page or two of suspense, Joseph admits that that last part was just to mess with him.
At the end of the Hell Pillar Climb, Joseph is about to slip off the wall. Caesar grabs his wrist... only to remember that he's exhausted, too. "26 seconds later, after Joseph said 'Don't let go!' thirteen times..."
In the anime, Joseph peeks in on Lisa Lisa while she's bathing. Later, in Lisa Lisa's epilogue, after a mention of her being his mother, he can be seen with an utterly disgusted look on his face.
Behold the glorious moment Joesph's brain finally breaks.
Joseph: Hey, Jotaro. This'll be my third crash landing. Heh, have you ever known anyone who's ever crash landed a plane three times in their life? Beat Jotaro: I will never fly with you again!
Before taking the camel, Joseph suggests crossing the desert by helicopter. Jotaro reluctantly says that he's not flying with a guy who has crashed three times in his life.
Hell, the whole "I'll show you how to tame a camel!" scene. Once everything is over, Joseph is covered in comical bandages. And when the camel slobbers all over him, he tries to pass it off as sunscreen.
And then the incident with Mannish Boy marks the fourth time Joseph crashes a plane. At that time, Jotaro had to fly with his grandfather again. And yes, the plane crashes. Jotaro mutters "I just knew it" as it happens.
The gang's battle with Arabia Fats and his Sun stand. Especially when Kakyoin, Polnareff and even Jotaro burst out laughing causing Joseph to think they've gone insane from the heat...then said tense moment becomes hilarious when it turns out they're laughing because they spotted a ridiculously obvious flaw in Arabia Fats' otherwise perfect concealment. Cue Jotaro taking the poor guy down with a single stone. It's almost worth it just to see Jotaro Kujo, hardass extraordinaire, laughing his head off.
Joseph and Avdol's bizarre adventure while battling Mariah. Especially when they get into a spot of trouble in the ladies' bathroom.
Avdol: "Disasters in the bathroom" is Polnareff's department!
Then they try to unstick themselves from the magnetic attraction that Mariah's Bast Stand afflicted with. Unfortunately it requires Joseph to stand up straight with his back to a fence while Avdol slowly slides downward off of him, causing no end of embarrassment when some bystanders catch the two...with Avdol's face at groin level with Joseph. Not to mention when an old lady sees this, for she had been earlier smitten with Joseph's "daring" nature (It was Bast's fault) but switches gears and goes apeshit on the poor guys.
In Part 3, During Jotaro's poker game Batman Gambit against D'Arby he keeps collected whilst D'Arby steadily goes even more insane. After the game is won, Abdul checks Jotaro's hand only to find that rather than having a hand that could beat D'Arby's 4 kings hand, Jotaro had absolute garbage. Cue Abdul and the kid dealer nearly face faulting and said kid letting slip that he had been dealing Jotaro a bum hand on D'Arby's orders. When Jotaro asks said kid about it, the kid runs for the hills.
Jotaro repeatedly stealing various objects with his Stand while locked in a jail cell in the very start of the arc, somehow managing to snag RC cars, weights, motorcycle helmets and an exercise bike. Some fridge humor comes into play when you realize that Star Platinum is a short range Stand.
When Polnareff runs into a still-living Avdol after he apparently died, he enthusiastically brings him back to the others, only for them to act completely nonchalant about it. They were all in on a plot to fake Avdol's death (with Hol Horse and J. Geil's unintentional help.) and didn't tell poor Polnareff because they feared he had a loose tongue.
In a darkly comical way, the way Dio bluntly told Senator Wilson Phillips (Who Dio was forcing to drive him around Cairo after the escaping Joseph and Kakyoin) that he wasn't going to let him go alive. Dio was so blunt with the poor guy its hard not to laugh.
Polnareff's first experience with an Indian toilet. A pig pokes its head up from the bowl. The bellhop hands Polnareff a stick with which to fend it off. And then the bellhop recommends letting the pig lick Polnareff's butt clean!
Hol Horse and Boingo's team up. When they're in an Egyptian taxi, Hol Horse is about to let Boingo out of the suitcase he was held captive in. Bear in mind, Boingo was on a plane, too AND Bound and Gagged. The very first thing Boingo does when Hol Horse removes his gag? Puke all over him.
Hol Horse: Still a little airsick are we?
Jotaro's reaction when he's called over to remove a mind control parasite from Polnareff. It's one of the few times you see him actually smiling.
On their way out of India, the heroes pick up the runaway girl from earlier, who's hitchhiking. She tries to get Kakyoin's attention by talking about how she'll have to wear a bra soon. The reaction?
Caption box pointing at the heroes: NO ONE CARES.
Anubis on being at the bottom of a river: "I'm so lonely!"
On a related note, the Part III Capcom game: DIO's time over lose animation has him rapidly backdash off screen. Couple this with Mariah's Noblewoman's Laugh pose and...
As the gang attempts to escape their submarine from Midler's High Priestess Stand, Joseph quickly trains them in underwater handsigns since they'll be wearing scuba masks. Polnareff shows off some signs he knows...which Kakyoin immediately figures out means "I can see your underwear." Polnareff bursts out laughing thanks to the mostly sensible Kakyoin getting it in one shot. Then they high-five and fist bump even as Joseph tells them off for messing about with the enemy right behind them.
The ending to the Wheel of Fortune chapter. Especially ZZ thinking he's killed Jotaro and proclaiming "I did it! I ended Part 3 early!" and Jotaro asking him who the main character's gonna be now ("And you better not say you.") Then the big reveal about ZZ...he's just a scrawny little guy with comically huge muscley arms. Cue the group bursting out laughing at his ridiculous appearance...and then laughing AGAIN when his Wheel of Fortune car Stand goes from a big muscle car to a smaller one which Joseph compares to a sheep losing its fur.
Diamond is Not Crash/Unbreakable
The Duwang scans. Any possibly dramatic or fairly serious moment is ruined by some of the most slapdash translation seen on a manga. Some of them have become outright memes in the community, with the more improved Part 4 scanlations retaining the more famous ones such as Koichi's "Get a feeling so complicated" as well as Kira's infamous "What a beautiful Duwang!"
Josuke: KOICHI REALLY STEALS? NO DIGNITY
Josuke's mother leaping onto Jotaro, thinking that he's Joseph, hugging him and telling him how much she missed "him." While still amusing, what made it hilarious was how stoicly he reacted to having such a cheerful and cute young lady hugging onto him;
Part 4 has it's moments, but the entirety of the arc, "I Am An Alien!", definitely deserves mention. Especially Mikitaka turning into a pair of dice and landing a perfect roll...while making Bruce Lee noises which even Josuke calls him out on.
The subsequent dice game scam that Josuke tries on Rohan afterward. And Rohan's house burning down yet Rohan not giving a damn about it because he's obsessed with trying to uncover Josuke's act of cheating.
During the aftermath of Rohan's house burning down (Which he's convinced was caused by Josuke,) Rohan keeps his cool.
Josuke: Uh, sorry about yesterday. The fire was, um, pretty bad, right?
Rohan: Yeah. I had a complete replica of the Drexel Heritage furniture used in the movie "Pretty Woman" valued at 2.5 million, which was damaged beyond repair. Not that I care or anything.
Josuke and Okuyasu eating at Trussardi's restaurant. Seriously, the entire thing! Especially the end where, even after ascertaining that Trussardi's not a bad guy, he still forces Josuke to stay behind and clean his kitchen top to bottom all because he busted into said kitchen without observing proper hygiene.
Old Joseph mishearing everything.
Okuyasu: 'Red Hot Chili Peppers'!
Old Joseph: 'Pop pop pop the popper'?
A minute later, Akira disguises himself as a SPW worker and attempts to assassinate Joseph. When caught, he fingers another worker as the assassin only to get punched out straight away by Okuyasu. And when Akira asks how Okuyasu figured it out so quick...
Okuyasu: I was planning on punching the both of you. 'Cos I'm not too smart, ya know?
Okuyasu: Koichi! Starting today, don't take baths! And don't brush your teeth, and wear the same underwear everyday! And breed lice in your hair! And fart all the time too!
There's something darkly hilarious about Rohan and Josuke laughing with each other during their game, then Rohan slamming a knife into his own hand and cutting his finger off to show he's not fucking around.
Also comedic in a rather dark manner is all the shit that Kira goes through in order to get back his 'girlfriend'. It almost seems like something from a Three Stooges show. What it leads to however...
A rare one from Kira.
Kira: By the way, do you have a tissue? Or a napkin perhaps?
Koichi: I don't...Why do you ask?
Kira: I see...Well you can use mine.
[Kira punches Koichi in the face]
Kira: Nosebleeds make a big mess, so I thought you might need one.
Another from Kira which has fast become a meme itself:
Kira: When I was a kid, I saw the Mona Lisa from my grammar school art book. The first time I saw her, with hands on her knee...How do I say this...I had a boner.
Even funnier is that despite coming from the above Duwang translation, it's actually completely accurate, down to the use of the word "boner (the page has the kanji for "erection" in it).
When Josuke finally catches up to Yuuya Fungami, the user of the Highway Star Stand that nearly killed him and Rohan in the town's hospital, he finds that Fungami is merely a bed ridden invalid, who tries to appeal to Josuke's good nature by asking whether he would really bully a weak and helpless cripple. To this, Josuke responds by healing his injuries with Crazy Diamond, and THEN:
Anytime Anasui tries to get a sweet moment with Jolyne; they're either just happenstance that he interprets as romantic opportunities or absurdly contrived set-ups by the man himself (such as getting FF to trip Jolyne just so she'll fall into his arms); either way they usually end at his expense.
Jolyne flipping off Kenzo in four different languages.
Jolyne, after regaining her memory, sees she wrote a note to herself that say "Don't forget to wear your panties". Her realization is priceless.
Hermes tries to cheer up Xander.
Hermes: Whenever someone says "This Monday was a bad day," they'll say to themselves that "Saturday will better." That's how we continue to live! No one lives a life of only Mondays!
Xander: I was arrested on a Saturday.
Even funnier: before that, Hermes offered Xander her panties. And he was actually interested, too (if only for a moment)!
Steel Ball Run
Stephen makes a horrible joke after going into a speech about a large block of ice holding the SBR trophy:
Stephen: Well, I think those comments broke the ice, don't you think?