Jocular mocking name of the famous cartoon character Pecos Bill.
Audrey: "Lets go to afternoon matinea. They are showing Pecos Bill. Lets buy some Dr. Pepper and popcorns too and have a jolly time!"
Avril: "You mean Feces Bill..! I dont wanna go to see Feces Bill, 'cause it stinks.. Get it? It stinks like FECES, LOL!"