Chorus Leader: "Their condition seems to jibe with these others. Now, does this cramping seize you in the wee hours?"
First Athenian Delegate: "Yes, and what's worse, we're worn absolutely raw by being in this condition! I mean, if someone doesn't reconcile us soon, there's no way we won't be f***ing Cleisthenes!"
Chorus Leader: "If you've got any sense, you'll cover up there: you don't want one of the Herm-Docker clan to spot you."
First Athenian Delegate: "That's certainly good advice." (1088-1095)
Aristophanes has worked in a reference to contemporary politics (contemporary for him, anyway) into this quote. The first thing you need to know is what a "herm" is. Basically, a "herm" is a special type of ancient statue sacred to the god Hermes. What made this statue special was that it was actually just a rectangular pillar, with a sculpture of Hermes's head on top… and an erect phallus at waist level. You can see a picture of these weird doohickeys here. These statues were used on the streets for various purposes, as boundary markers, sign-posts, and so on.
What's this all have to do with Athenian politics? Oddly enough, one night in 415 BCE (4 years before Lysistrata's theatrical debut), some hooligans went through the streets and smashed the faces and genitals of the herms. This was considered especially bad luck because it was right before Athens sent a massive naval expedition against its enemies in Sicily—an expedition that ended in total failure. When Lysistrata was performed, the culprits in the "Herm-Docking" had not all been identified, and Aristophanes is hinting that some of them might be in the audience (making the First Athenian Delegate want to cover up).