This Mike Wartella cartoon is from the episode The Adventures of TaunTaun / Everybody Loves Rayman.
Summary of Skit
Man #1: Look! Up in the Sky!
Woman: It's a bird!
Man#2: It's a plane!
Man #3: No, Moron! *Walking cane knocks on him* It's a bird!
*bird poo drops into kid's head*
Bird is not a plane