like a frog.
[Edit by Fran: The poster is referring to a quote by Biker #2 in the Fourth of July fireworks scene. Here's some of the dialog from the scene:
Biker #1: "Wooeee...look at this crowd! There's bound to be lots of pussy on the hoof in a crowd like this."
Biker #2: "All swelled up with patriotic feeling and ready to be humped like a frog."
There are plenty of unplayed words in this scene, by the way. I've got my eye on a specific V: Vegas.]