It's not wise to drop in on a wookie...
My friend pointed this poster out to me in a a Brisbane shopping centre the other day. It was sitting in the window of a picture-framing store. Ah, pop culture. How I love you.
Star Wars: Episode IV - A New Hope (1977)
[R2-D2 and Chewbacca are playing the holographic game aboard the Millennium Falcon]
C-3PO: He made a fair move. Screaming about it can't help you.
Han Solo: Let him have it. It's not wise to upset a Wookiee.
C-3PO: But sir, nobody worries about upsetting a droid.
Han Solo: That's 'cause droids don't pull people's arms out of their sockets when they lose. Wookiees are known to do that.
C-3PO: I see your point, sir.