From the set of the latest Indiana Jones installment

Spielberg:  Oh, crap!  We forgot to make the crystal skull.

Lucas:  Oh man, you're right.  Quick!  Send Joe out to get something we can use.

(one hour later)

Joe:  Dudes -- check it out!  Can you believe this cool skull I found?

(Lucas and Spielberg look at the crappy, obviously plastic alien skull)

Joe:  Yeah, I found that at Spencer Gifts.  I was gonna get you some of that fart powder to go with it cause, man, that shit is funny.  Oh!  And look! (turns switch on the back of skull)  It's got a lava lamp in it!

(Lucas and Spielberg look at the lava lamp, then at each other)

Spielberg:  Awesome!

Lucas:  Woa -- that is cool!  Alright dudes, let's make a movie!