… you’re any character in a Victor Hugo novel.
… the guy you just shot up complains about the damage to his shirt.
You’re up against a Sicilian, and death is on the line.
Or you’ve gotten yourself involved in a land war in Asia.
…you decide not to cover that heel with any armour, the Trojans arent that good a shot anyway.
…you look up and see great yellow spaceships hanging in the sky in much the same way that bricks don’t.
…you notice a crop duster crop dusting where there’s no crops.
…a Vogon decides, before he has you chucked out the airlock, to see what you think of this poem he’s working on.
You’re made of clay, and get to play with Mr. Hand.
When you are threatened, and just to make sure, you ask, “is that a threat?”
They say, “no, that’s a promise.”
You upset a boss with a freaky looking white cat.
You run into a four foot high talking salt shaker.
There’s a helicopter scene and the director is John Landis.
You’re assigned to an Antarctic weather outpost with Kurt Russell.
Yama-Dharma takes a dislike to you.
You hustle some rube from south Alabama name of Willie McCoy and he comes looking for you and your drop-top Cadillac.
Your name is Gruber and this guy named McCain takes an interest in your little scheme.
A crazed albino, with a moaning black sword , is shouting your name.
You are assigned gaurd duty, for a prisoner named Conan.
You’re the senior officer on a project being overseen by Darth Vader.
… your birth certificate has an expiration date.
…you’re taking a shower in a strange motel and suddenly you hear screeching violins.
You sit down for a friendly game of poker with a redheaded guy named Lazarus or Woodrow.
The best part is that this works for classy stuff, too. Henry V, Richard III – both have awfully high body counts… 
You answer a knocked door, and a very muscular man asks you if you’re Sarah Connor.
You see a large, leathery egg suddenly open up like a flower.
You’re a census taker an the man you’re interviewing has fava beans and a nice Chianti on the countertop.
One of your bandmembers has become infatuated with a Japanese Avant Garde artist.
You’re giving your son a crew-cut with your clippers, when you see three sixes on his scalp.
Yoy click on Straight Dope Message Board on your list of favorites, and end up with a Page Not Found.
You’re the only one who can see your friend Harvey. A burly guy in a white lab coat asks you, “What’s a pooka?”
Hey! I’m a geezer. Whadaya want from me?
Geezer