I'm really not sure which kind of comedy suits this strip the best. Do physical, slapstick jokes work more, or do more thoughtful, verbal jokes fit? I guess it's better to have a mix of both, but personally I find verbal jokes come more naturally. This is one of those slapstick moments.
(On an unrelated note, I think the sign on Billy's sign is funny. I laugh every time I hear someone say "5 bucks a pop." It's such an outdated expression.)