What's the sound of one hand clapping?

Lisa: Bart, I have a riddle for you. What's the sound of one hand clapping?

Bart: Piece of cake.

Lisa: No Bart, It's a 3000-year-old riddle with no answer. It's supposed to clear your mind of conscious thought.

Bart: No answer? Lisa, listen up!

Give up, Homeboy, there's a six-stroke limit.

Give up, Homeboy, there's a six-stroke limit.