Bart: [hammering away]
Homer: Bart, you don't have any hobbies, do you, boy?
Bart: No, not really.
Homer: Well, that what I... Wait a minute, what are you doing?
Bart: Building a soap box derby racer.
Homer: Ohhhhhhh! That's a hobby!
Bart: Hey, so it is!
-- "Saturdays of Thunder"