"Is not love not unlike the unlikely not it is unlikened to?" Also (and sorry I can't find a clip), from the Simpsons during breakfast... "Butter up that bacon, boy."
I go out of my way to use the Larry David thread title quote. I had a friend who thought I was being original for almost a year. I forget which episode of the Simpsons, but the context is Bart being sad (about his dog, maybe?) and confiding in Homer, to which Homer replies: "There, there...shut up, boy." I find it works in a surprisingly large number of circumstances.
My mom and her brother used to always quote this scene to each other. I still say "Pecan Piiiieeeee" whenever it's at all relevant.
"Noooo way Kimosabe." From Step Brothers everytime someone asks me to do something I don't want to do.
I always Omar lines and people have no idea what I'm talking about, or a nice Clay Davis "Sheeeeeeeeiiiit". YOU GET NOTHING! Its shameful how many people don't get that reference. I quote Archer alot too, but have stopped cause it encourages my idiot roommate to misuse "Danger Zone" more than he should. Oh, also this scene: "Check check check". I once said it to a waitress, she actually got the reference and cracked up. One of my finest hours. Also, I make all my friends see Rounders so they will know where "Pay that man his money" comes from.
Seconded. Also there's this one quote from some random episode of Las Vegas, where Jon Lovitz guest starred. I can't even remember the exact context nor could I find a video, but he was tending a bar and some client kept pestering him about his drink. Finally, to the question "Where's my drink", he bellowed "IN MY BELLY!" Great line to use at random times as an answer to any 'where' question.