From A New Hope:
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. I suggest a new strategy, R2: let the Wookiee win.
While Han was probably joking, it raises the question; was Han basing this on personal experience? Had he ever seen Chewbacca rip anyone's arms off?