Mr. Fluffypants is a character in the Disney Channel animated series Phineas and Ferb. He appeared in the episode Spa Day. He was found by Doofenshmirtz while checking the mail and he took him in, naming him Mr. Fluffypants. Because he's so fluffy, he looks like he's wearing pants and he reminds him of his Uncle Fluffy Pants. While Mr. Fluffypants is messing with Doofernshmirtz's inators, Perry the Platypus believes that Doofenshmirtz is behind the disturbances, but Perry discovers the truth when Mr. Fluffypants messes with the inator that made Phineas and Ferb's spa disappear. In the end, Mr. Fluffypants had an original owner, who reveals the feline's real name is Mr. Cat. Doofenshmirtz then had to give him back and was not happy about it.
http://disney.wikia.com/wiki/Mr._Fluffypants
http://disney.wikia.com/wiki/Mr._Fluffypants