There's a Mexican slang expression that's always kind of stuck me as funny: When young Mexicans want to express that something is really cool or great, they say ¡Que padre! or "How father!" And if something is really, really cool, they might call it padrisimo, which in kid talk translates as "wicked awesome!"
I think the "how father" expression strikes me so funny because for American kids, probably the absolute farthest thing from cool is their dad (though I should note that my dad, who might read this blog, is quite cool).Another funny slang expression they use here is ¿Que pex? which means "What's happening?" but translates more directly as "What fish?" And here in Mexico City, I've notcied that people like to say ¿Que pasó? instead of ¿Que pasa? to ask "What's happening?" This is unusual because ¿Que pasó? is in the past tense, so it sounds like people are asking you "What happened?" I instinctivly want to respond with "when?"
Of course, it's not like English doesn't have some funny greetings and slang expressions. "Cool" itself must seem like an odd term to English language learnings who listen for literal meaning, and "Groovy" is probably quite confounding as well. And for greetings, I bet "What's shaking?" and "What's cooking?" seem downright ridiculous.