In Gotham City Garage, Kara Gordon and Dick Grayson are fleeing a guardian robot and Nightwing suggests to get out of the facility and get on their bikes because the guardian obviously won't leave the base to chase after them. Then the guardian proceeds to do exactly that.
Nightwing: Let's ride! There's no way that thing can leave the facility— We'll be free and clear! [the guardian robot leaves the facility and chases after them] Supergirl: You were saying?!
Urk: Cheer up, Paperinik. Things could be worse. Paperinik: Excuse me? Things could be worse? We're stranded in a wood deep in enemy territory, with no means of transport, no weapons, no food and it's at least fifty degrees below freezing point! How could it get any worse than this? Urk: It could be snowing. (snow starts falling) Paperinik: Are you satisfied now? Urk: Well, at least there aren't any wild animals around. (wolves howl in the distance)
Minor Captain America malcontent "Bull's Eye" was a villainous agent of HYDRA and an ace marksman who had a strong target motif in his costume. Yes, he was eventually killed when someone shot him directly through the bullseye on his chest.
Now there's the merc/murderer/Psycho for Hire Bullseye. His costume has a bullseye on his forehead. why? Because he also has one carved there. He has a target on his head out of costume (subverted when he spent a year and a half real-time dressed as Hawkeye).
In New Krypton, Supergirl's father Zor-El tempted fate several times:
In "Superman: New Krypton Special", Zor says now they have powers "We'll never be in harm's way again". he got murdered shortly after. And New Krypton got blown up.
In Supergirl vol.5 #34 Kara questions the wisdom of having a Brainiac's robot keeping Argo's shields up, and asks what would happen if it woke up. Her father reiterates over and again it can't and won't turn itself back on. Despite everything, the robot woke up and nearly killed them.
Supergirl's father is physically incapable of keeping his mouth shut. In The Supergirl from Krypton he had this to tell a while before a meteor storm struck Argo and forced him to send his daughter to Earth:
Zor-El: Our child can grow up safely as long as the leaden shield under our community wards off those kryptonite radiations!
In the modern version of The Supergirl from Krypton, Kara thanks Harbinger for making her welcome and tells "I think we're going to be friends for a long time". A few minutes later, Darkseid's army assaults Paradise Island and Harbinger dies trying to protect Kara.
In Supergirl vol.6 #19, several Luthor's henchmen are trying to seize Supergirl. Two of them comment that she's just a kid and they'd hate to see what she could do when she grows up. Cue Power Girl -an adult Supergirl from an alternate universe- showing up and trashing them.
At the beginning of "Superman Supergirl: Maelstrom" #1, Supergirl notes that it's been a very quiet week and she thought she'd have more action when her cousin asked her keep an eye on Metropolis while he was away. Cue a Darkseid's minion arriving on town and flinging cars away.
Supergirl: Oh no... The second I think good thoughts...
In DC Retro-Active Superman 1980's, Earth-One Superman has a nightmare where -among other things- he sees Supergirl dying. When he wakes up he barely remembers his dream, but he is very shaken and frightened, and he calls his cousin to ask her to be careful. Kara dismisses his fears, reminding him that "There's not much that can hurt [her]"... and then she mentions that the morning sky is red...◊ A little after she'd get killed in the Crisis on Infinite Earths.
When Kara and Stephanie Brown -Batgirl III- first team up, Supergirl wants to charge in and take down the villains, but Stepth suggests that it is not a good idea. Then Kara asks her, "It's the first Supergirl-Batgirl team up, what can go wrong?". Steph made sure to give her a sarcastic "You were saying?" when the pair was overwhelmed by Toyman's robots.
Linda does this twice in Action Comics #270. At the beginning, she is bored and wishing she had loads of important rescues to perform. All of sudden she has to undertake a space mission and fight a super-villain undersea to save Atlantis right after. After returning home, she thinks "What an action-jammed day! To think I was sad, earlier, because I didn't have enough action! The rest of the day will probably will be quiet..." Cue Batman and Robin needing her help.
Lex: You see this robot was built specifically to negate your vaunted Kryptonian strength. It would take a rocket forged in another dimension to...
Bizarrogirl: Supergirl decides to explore the inside of Godship even though Bizarro warns her it's a bad idea. She believes he means it's a good idea and flies off, stating: "Don't worry. I'll be fine." The godship smashes her through the planet.
After all Kryptonite on Earth has been turned to iron, a Daily Planet headline declares Superman had become really invulnerable. Jimmy Olsen screams that Superman has nothing to be afraid of now. Shortly after a doppelganger begins draining Superman's powers.
Clark has to come up with a way to stop a swarm of ants, and thinks "But there's no hurry — No immediate danger!" A second later, two monstrous ants kick him from behind.
In issue #238 Superman sets out to arrest a pirate band. Since they appear to be only armed with guns he thinks: "Maybe this task won't be as tough as I figured". Then they start the magma-hose.
Spider-Man thinks "This must be your lucky day!" when he runs into several crooks. Then he runs into Doctor Octopus, nearly gets killed, several cops try to arrest him, and he runs out of web-fluid. He decides "Hero, your lucky day — This is not!"
Several guards seeing Lex Luthor to his cell assure that he will not walk free this time and they got him good. Good grief...
Spider-Man is aware that he should have kept his mouth shut when he made a remark about trite death traps:
Peter: Huh? The old "suddenly shutting door" trick, eh? I was hoping for something more imagina— Whoops! Machine guns in the floorboards — something tells me I should have kept my mouth shut!
In Ultimate X-Men series two, calling them "Nimrod" sentinels. Nimrod is Hebrew for rebel. Seriously, it's like Ult-Obama and minions (anybody who sends WMDs after kids is NOT a hero) were just asking for a Sentinel rebellion. For the record, they're named after Biblical Nimrod (Genesis 10:8-9, described as a "mighty hunter before the Lord), who may be by some, including myself, conflated with the king who supervised the construction of the Tower of Babel. Nimrods are indeed "mighty hunters" of mutants, especially innocent children, but they are especially prone to rebel. Any use of Sentinels appears to be a bit of Tempting Fate, considering how often they rebel against their creators across the various X-Men media. The one exception that comes to mind would be at the end of X-Men Evolution, when Apocalypse was trying to turn the world into mutants by means of radiation from satellites. S.H.I.E.L.D. in that show using specially reprogrammed Sentinels to try to destroy the satellites before they could fully activate/charge/whatever was a good move, and justifiable considering that hundreds of millions of people all around the world (if not a billion or two) would have DIED, probably in torment, from Apocalypse's actions.
Anytime you hear a supervillain say anything along the lines of "Batman"? He doesn't even have any powers!" Expect a Curb-Stomp Battle.
There's the similarly related "Batman? He's just an urban legend!" or the like, although this is generally more for mooks.
The Jedi-killing bounty hunter Durge is practically begging to die with this line:
"You think that was going to stop me?!? I was once buried alive for sixty years! If that didn't kill me... if the Sith and the Mandalorians and the Bloodboilers of Kragis couldn't kill me — then you will not kill me!"
In Marvel: The Lost Generation, the Black Fox tells his First Line teammate Yankee Clipper that he's going to propose to his girlfriend and retire immediately. Black Fox is all smiles and sunshine, extremely optimistic about the new life before him. Before he gets the chance to pop the question, a supervillain murders his girl.
In one arc, Linus gets a new hobby, drawing on air. Simply put, he traces things on air with his finger, and being a Mr. Imagination, perceives it as art, one that costs no money and needs no materials. However, he enjoys it a little too much, saying "nothing can interrupt your work! Nothing, nothing!" And then it starts to rain.
In another arc, Linus' hobby is building snowmen; he builds lots and lots of snowmen. However, he gets a little Drunk with Power, and starts talking to them like a general leading an army. "I am your leader!" he shouts to his "troops". "Stand behind me and you will be invincible! Nothing can stop us, nothing, nothing,NOTHING!" And then the sun comes out and melts them all.
Garfield likes to play with this trope. If someone says things can't get worse, they will (usually with Garfield warning not to say it). However, if a character admits things could get worse, they get worse.
In December, 15, 2011, Garfield told a spider that was under a mistletoe to forget it and that he'd rather kiss a dog. Odie then showed up.
In The Order, college baseball and track star "Calamity" James Wa was described on the cover of Sports Illustrated as "The Boy Most Likely to Succeed." And his nickname is "Calamity". He got into a car accident on the way to a state finals meet... and lost his legs. James went into engineering instead of sports afterwards, and developed advanced prosthetic legs that made him a millionaire by the age of 22, so by all measures he has succeeded, but... it's not the same.
In Issue 11 in the Transformers Ongoing comic, Vortex hoped that the Autobots would show up so he could scrap them. Cue Optimus Prime plowing through the wall ramming him.
U.S. Acresplayed with this trope when it was a beautiful day and Orson said even Lanolin couldn't ruin it. To prove him wrong, she yelled she had just washed her car. It started raining soon after.
In Death of the Family, Batman claims that Joker doesn't actually know the Batfamily's identities. Considering what's been happening so far, Batman is likely setting himself up for a rude surprise.
At the end of Moon Knight's current run, the hero utters that he'd rather face a Robot Apocalypse than live in Los Angeles any longer. The blurb on the bottom of the page? "Moon Knight Will Return InThe Age Of Ultron"
Subverted, in that Tonk Stark straight-out told him that Ultron was trying to wipe out humanity and that it will happen soon. Moon Knight was just venting frustration at LA and Hollywood.
Twilight: Well, hopefully that means no one is here and we can just walk on through with no issues! Rainbow Dash: Pfft... saying things like that just means you're begging for something to happen.
From the short in Issue #1: "Its not like I'm going to get in trouble in the three seconds she's gone." Says the pony best known for being easily distracted.
Constantly with the Nightmares toward Spike as they don't see him as a threat in the second story-arc. Likewise Nightmare Rarity proclaims what could Spike hope to accomplish against her... yet why would she take the Fire Ruby he brought for her if she considers it "worthless"?
During the Cobra Civil War in G.I. Joe (Marvel series), a groups of Joes sneak through a tunnel and get attacked by rats. One yells "At least it can't get worse!" Another adds "How could it?" Cue two of Destro's soldiers pouring soup down a grate.
Shakara: The frog-alien commander who oversaw the convicts dumped on the sentient Death World by The Hierarchy crashes down on the planet along with his crew after Shakara intervenes. He just has to boast that surviving for a few hours after they transmit their Distress Signal should be a walk in the park. Obviously, they all die within seconds.
Mortadelo y Filemón: In a short story, the Superintendent is checking the TIA's account book, and has just reprimanded Filemón over an incident that has cost them a lot of money. No prize for guessing what happens after this line:
Super: This is incredible! May my mustache fall if I find an even higher note of expenses!
The Súper is telling the pair about their next assignment. It looks dangerous, but the Súper assures that their lives will not be at risk. Filemón, worried, asks again whether it is true they will be safe. "As true as this closet is made of wood!", the Súper replies, hitting a nearby closet for emphasis, "May the world fall on my head if I'm lying!". The desk globe that was on the closet falls right on his head.
Infinity: the leader of the Builders demands that the Avengers and their allies surrender, with the Builder forces heading straight towards Earth. Thor, wishing to avoid further bloodshed, throws Mjolnir into space and agrees to surrender on behalf of the rest of the heroes. The Builder, rather than take a hint and work with the Avengers rather than against them, proceeds to strike Thor, mock him for thinking Earth will be spared, and declare that humanity and its heroes are weak and doomed. Cue Mjolnir reentering the atmosphere at meteroric speeds and slamming into the Builder's stomach, pretty much obliterating his midsection. Thor had simply been stalling for time in case he couldn't talk the Builders down. The rest of the Builder forces are ripped apart in orbit by the Avengers and their allies shortly after.
Dastardly & Muttley: Richard Atcherly and Dudley Muller find themselves surrounded by cops right after Atcherly declares "There's no stopping us now!".