pull my finger

verb1

1. •
   A phrase used when playing a prank regarding flatulence, in which someone is asked to pull the finger of the person playing the prank, who simultaneously flatulates so as to suggest a causal relationship between the pulling of the finger and the ensuing expulsion of gas.

   • Bob: "Oh, how do you play this game?"
   • Charlie: "Well, Bob, just pull my finger."