The Search for Terrestrial Intelligence is probably one of my favourite episodes:
"You sound like a writer for Fox News"
"Um, I already am"
"Oh, I guess that's where you got your style guide from"
"Mmm-hmm"
"No one, on Earth, is gay"
"But I saw one this morning!"
"You might not have been on Earth then, motherfucker"
"[Huge, exaggerated gasp]"