Another cool cartoon.....
Teenage Mutant Ninja Turtles
Picture it. Japan. 1965. Oroku Saki, a devilish and jealous young chap, double-crosses Hamato Yoshi, his fellow member of the Foot Clan, by stabbing his shirt to the wall, which keeps him from bowing to their master. When Hamato pulls the knife from his shirt, everyone suspects a murder plot, and he's banished from the clan forever. Hamato soon takes over and leads them to a way of crime, forever changing the scope of ninja acceptance forever, and the eventual size of Hamato's tail to boot.
In disgrace, Hamato moved to the sewers of New York City. Hamato moves into the sewers, because he's too poor to move anywhere else and too new to have heard about the myriad Spanish trailer parks outside the city that even someone on a ninja's salary could afford, and his only friends are the rats. Until, that is, some poor kid trips and his bowl full of little turtles falls on his head.
Weird pink ooze spills into the sewer, and Hamato is most unpleased. He doesn't know it's mutagen yet, but honestly, it's ooze and it's in a sewer, so no matter what it is, it's not something he wants to clean off the turtles.
But indeed, it is mutagen, the rare experimental gloppy stuff that turns whatever touches it into the animal it's been in contact with most recently.
The little turtles morph into big turtles, and Hamato inexplicably morphs into Splinter, despite very clearly having touched turtles ten seconds prior. Guess the mutagen has a selective memory. Over time, he taught the turtles the ancient art of ninjitsu, which according to the show involves a lot of weapon-twirling and party hollars. And that's how they became the Teenage Mutant Ninja Turtles!