I hate to disappoint Penny, but yeah, it was Coors Light (see hypoxic's post).

And ParU, "check six" is typically fighter pilot parlance (hah! big words!) for "look behind you to make sure there isn't somebody there who's going to shoot your a** off" (more or less). If you're looking for a particular movie or something for that quote, probably too numerous to count, I'd have to say...

-There's someone in my head, but it's not me.-