Patrick's underwear is a character who appears in the episode "The Gift of Gum."
Patrick's underwear is an old pair of underwear that is white and light blue in color. It also has pink gum on it from Gummy.
Patrick's underwear was first seen after it crawls out from Patrick's Gummy. It crawls onto SpongeBob's face and tells SpongeBob in a raspy voice that he isn't Patrick. SpongeBob screams in terror and Patrick's Underwear crawls away.