Spidey has had some of the craziest moments in comic book and animation history. Aside from getting superpowers after getting bitten by a radioactive spider, he's been a monkey:
And a pig:
And he's had really painful colonoscopies:
He's had some strange villains as well:
But what about the strangeness that Spidey has had to go through personally? Being a mutant spider/man is bad enough, but all the other crazy side effects and changes he's had to go through over the years are pretty insane!
Right in the middle of a fight with Morbius, Spidey starts sprouting four more arms — all because he drank a potion that was supposed to get rid of his spider powers.
What naturally comes right after getting four more arms?
In the comic, Spider-Man drinks another potion that returns him back to normal. In the cartoon version of the story however, he continues transforming into a man spider!
Here's a clip from that epic saga:
Man Spider 2
After getting kissed by the Queen, a villainess in The Spectacular Spider-Man #15 comic, he turns into a giant spider with the ability to shoot webbing from his wrists, much like Spider-Tobey.
In The Amazing Spider-Man #437, Spidey gets sprayed in the face with Plantman's mutagenic flower. He convinces Plantman to get him the antidote after throwing the villain into his own mutagenic goo, turning him into a tree. Plantman wanted the antidote, but it looks as if Spider-Man just went off and left him as weeping willow! (Or whatever tree it was).
After coming in contact with a device that cures Curt Connors of his lizard-ness, Peter later turns into the Spider-Lizard. Because, apparently spiders by themselves aren't bad enough.
In 2010, there was a two-issue comic that featured all of our heroes “hulkified” into Hulkpool, Spider-Hulk, No-Thing, Hulking Torch, Hulklops, Wolverage, Hulk Machine, and Thorr, among others.