Wait—an Ancient Greek drama that's colloquial? Is that even possible? Didn't people back then just walk around muttering "thee" and "thou" (or the Ancient Greek equivalent) into their long fuzzy beards?
Well sure, some of them probably did—and those are exactly the old fogeys whom Aristophanes mocks with his chorus of old men. In fact, the language of Lysistrata is still extremely fresh, lively, and colloquial, even after all these years. Plus, it's really clever—seriously, practically every other word in this play has some kind of smutty joke.
Even the boring old Magistrate can't keep his double-entendres under wraps:
By Poseidon the Salty, it serves us right! When we ourselves abet our wives' misbehavior and teach them profligacy, these are the sort of schemes they bring to flower! Aren't we the ones who go to the shops and say this kind of thing: "Goldsmith, about that choker you made me: my wife was having a ball the other night, and now the prong's slipped out of the hole. Me, I've got to cruise over to Salamis, so if you've got time, by all means visit her in the evening and fit a prong in the hole." Another husband says this to a shoemaker, a teenager sporting no boyish cock: "Shoemaker, about my wife's tootsy: the thong is squeezing her pinky winky, where she's tender. So why don't you drop in on her sometime and loosen it up so there's more play down there?" (403-430)
Yeah, the least colloquial (and most G-rated) phrase in that hunk o' text is "By Poseidon the Salty."
We have to add one word of warning: none of this hilarity will come through if you get the wrong translation. Back in the day some translators tried to do crazy things like translate the whole play into rhyming poetry (didn't work out so well), and they usually tried to clean up all the X-rated lingo. So do yourself a favor: find a translation that's informal and bristling with swear words. Not only will it be more fun to read, but it will be much more accurate to the original as well.