Pas de cheval: because if it's supposed to make you look like a horse then you KNOW it's gonna be all kinds of elegant and graceful.
Actually, pas de cheval is at least one of those steps that is easy to see how it got it's name. Yeah, okay, horses kinda do that. Have you ever seen prancing ponies? You know, show horses? They sort of do weird little steps like that. And all horses kind of paw the ground, right? Anyway. At least it's better than pas de chat which doesn't quite capture the "cat" feeling to me. Everyone I have demonstrated it to tells me it sorta maybe looks like when you startle a cat and it jumps straight up in the air like "WO! DUDE!" and then quickly goes back to pretending it owns the place.
On the subject, sometimes you find the funniest things when you google the names of ballet steps. For instance: this Yahoo! question and answer. What does pas de cheval mean, guys!? It means you ought to ask in context, because maybe you wanted to know about a song that your boyfriend played you or whatever but I'm guessing not. And if you went to ballet class the next day and told your teacher that it means "I have no horse" then I bet it was pretty amusing for everyone else in class.