very very similar to
pool hopping.
get thee to a fairly
big ass bus stop, one where many busses meet. pick a
bus.
ride it. get off when you get
bored. choose another bus. ride it.
get off when you get bored. repeat.
this is actually a great, and cheap way to spend a day, as well as travel the world. it can be done with city busses or even greyhounds. with the former, i suggest a daypass or some other kind of unlimited bus pass, and the latter might prove to be awfully expensive.