The Isle of Lemnos in the myth of The Argonauts. An island full of beautiful warrior women who claim all their men are away fighting. Of course you can stay as long as you want, eat and drink the food, help yourself to their treasures and have your way with the women. They frequently sacrifice men to Artemis once they've drugged them with the wine. Thankfully the lone female Argonaut isn't fooled.
The Sirens were a subversion. Their singing is hypnotic and lures sailors to their death but when the Argonauts came across them, the Genre Savvy witch Medea tells Orpheus to play his harp and drown out their song. This not only saves the Argonauts but future Schmucks as well since the Sirens throw themselves into the sea and drown themselves.
The tale of Pandora's box. All she had to do was not open the box, and everyone would be happy. But no, she just had to see what was inside. So she opens it. Some variants of the myth support this, while others support the concept that Pandora herself was the bait. The rather misogynistic writings of Hesiod claim that Pandora was created as a punishment for man, so that all her descendants, e.g., women, would torment humanity. All men had to do was not accept her as a gift and they would be free of the associated evils, but they ignored all the warnings about accepting gifts from the Olympians.
Still other versions say that Pandora could never have left her urn unopened; the Olympians had given her insatiable curiosity along with her many fine and desirable qualities.
There's also the story of Orpheus, who went to the underworld to retrieve his dead wife, but was warned not to look back at her before he got back to the world of the living. He looked back. She died again because he did wait; he just didn't wait long enough. He was out of the underworld; she was not. Not completely, anyway. Additionally, Hades made her follow him in complete silence. As far as he was concerned, Hades could've been a complete douche who was leading him on and making a complete fool of him. Think about it: the person who kidnapped your wife suddenly says, "Alright, she'll come with you, but you have to walk all the way back out of here and never look back. Don't worry, she's there, she's following you... You can't hear her, but it's alright, she is. Trust me." Damned if he does, damned if he doesn't.
A clue may be in that Eve's rendition of the prohibition had an additional part against touching the fruit that wasn't in the original. Which makes sense; if you're not going to eat it, there's no reason to intentionally touch it. Well, according to tradition, the serpent backed her into the fruit as he was talking, thus proving that touching it wouldn't cause death, and casting additional doubt on the veracity of the real command.
In Mark Twain's Puddin'head Wilson, the eponymous character muses in his almanac that a better way to keep Adam from eating the apple would be to tell him not to eat the serpent.
To get back at Cuchulainn for knocking her up and then marrying Emer instead, Aoife sent her son out into the world with two conditions: Challenge every warrior he meets, and never ever ever reveal his name. Naturally, when Cuchulainn gets challenged by some kid, cue the Curb-Stomp Battle. Then Cuchulainn notices a really familiar-looking ring...
Bluebeard's wives invariably fell victim to this trope. Although it's never explained why his initial wife was killed, as she couldn't have seen any of his dead wives.
There's also original "Damned if you do, damned if you don't" fairy tale, sometimes named "Dark world". A king and his companions were on a quest and, in their wandering, ended in a cave-like, long, underground passage. They kept moving until they came into a part of passage where no light could be started or exist (titular "Dark world") and felt rough things or pieces of things under their shoes. Suddenly, a voice was heard "If you take those, you'll regret it. If you don't take those, you'll regret it." Some people chose not to take those, some chose to take one or two, just to see what all the fuss is all about then moved away from weird things. Finally, after 3 more days of wandering and lots of danger, they got out of the cave. After they looked at their pockets, they found they took rough diamonds. Now, those that didn't take anything, regretted it and those that did, regretted they didn't take more than one or two!
Psyche nearly averted this. When her husband Cupid told her never to look upon his true form, she was perfectly fine with it until her sisters convinced her that he might be a hideous monster (despite that she had previously felt his body and had plenty chance to feel his face). At least she only had to deal with a Mama Bear that was already mad at her instead of the Deader than Dead fate that usually befalls those who look upon undisguised gods. And then, when she was sent to bring back the beauty of Persephone in a box, she peeked. (Lucky he had decided to reconcile and came to save her.)
The Odyssey. "Hey, we're a bunch of incredibly hungry sailors on an island inhabited by the juicy-looking cattle of the sun god! What's that, Odysseus? We can't eat them? C'mon, what could happen, it's not like we can piss off the gods even further..." They decided that whatever the gods were going to do would be better than starving to death while stuck on that island. (And they might not have been particularly wrong — drowning may or may not be a particularly nice way to die, but it's better than starving.)