Bloo finds a strange rock digging in the yard and it is declared to be a fossil by Phineus B. Vurm, the bookworm imaginary friend. Bloo treats it as a pet until Frankie reveals it is actually petrified feces.
Mac and the other friends start a car wash to pay for a porcelain poodle that Bloo broke. To help, Bloo throws mud at every car that goes by to get more customers.
Mac and Bloo have a staring contest and Eduardo tries to talk to them only to think they are frozen solid, consequently getting Frankie to tell him about it.
Mr. Herriman tells Bloo to sort the trash as punishment for him hosting a mud-wrestling tournament in the living room. Mac comes along and talks Bloo into pretending it is fun so that other people will want to do it.
Mac realizes that he accidentally created a new imaginary friend named Cheese. Cheese is allowed to stay at Foster's like Bloo, but Bloo has trouble dealing with his new brother Cheese.
Wilt is getting tense at Creator Day when Mac keeps mentioning the word "creator" to him. Wilt suddenly leaves in the middle of the night and the Foster's friends look for him.
Mac and Bloo both develop a crush on Frankie, and try to stop her from having any contact with any guy. Eventually, they follow her on a date while in disguise.
