Bart: Boys and girls, Mrs. Krabappel, I come before you today to solve a riddle that has plagued mankind for centuries: What has four legs and ticks?
Milhouse: A walking clock?
Nelson: A walking clock!
Martin: I'd wager he has some variety of walking clock in that box!
Edna: Bart, is it a walking clock?
Bart: What?.....No, it's my dog.