In Batman: The Dark Knight Returns, the bright yellow logo on Batman's chest is revealed to be Schmuck Bait, as he deliberately included this target in his costume to bait Mooks into shooting at his well-armored chest, not his head.
The Punisher has said the same thing. He wears the skull on his chest (over his body armor) so they don't shoot the one in his head.
Batman: The Batmobile has an unlabeled large bright shiny red button in easy reach of the driver's side. When pressed, it floods the car with sleeping gas, the driver's side first and foremost. Why? In case the Joker ever steals it. Because The Joker would never be able to resist pushing an unlabeled large bright shiny red button just to see what happens.
Employed in a Felix the Cat comic where he figures out that the person who just stole a set of jewelry is a compulsive reader. So he has the police set up upside-down signs around the city and waits for someone to do a handstand to read the sign and have the jewelry fall out of their pockets.
Ultra Comics #1. Its cover has the eponymous Ultra warning the reader that only they can save the universe and themselves by not reading this comic. Earth-20's Atom didn't heed the warning in Society of Super-Heroes: Conquerors from the Counter-World #1. Will you?
In Sonic Universe, Silver, Jack the Metal and Larry the Lynx are going through a dungeon especially designed to be impassible to anybody who doesn't have Chaos Powers. They come across a long corridor with the walls, ceiling and floor covered in holes.
In White Sand, Kenton's looking for the last sphere to finish his Fetch Quest exam when he spots it in the centre of a perfectly round and flat plaza of quicksand - in the middle of of mountains. He goes for it, wondering only for a moment what kind of winds would create such place... and of course it turns out to be not a geological feature but a nest.
In Red Sonja: The Art of Blood and Fire Gribaldi announces his first appetizer course to Emperor Samala: pate with Khitaian mushrooms. Minutes later Gribaldi mentions that as any true gourmand knows, Khitaian mushrooms are deadly poisonous.