It was going to be "Rule of Tree", but we twigged onto another pun.

Transcript

Trooper 4: Sorry, but there are very strict penalties for breaching the secured perimeter. I'm sure you understand.
Luke: I draw my laser sword.
[SFX]: Whooom!
[SFX]: Pow! Pow! Pow!
[SFX]: Deflect! Deflect! Deflect!
Luke: I swing at the bike! 14.
[SFX]: Whooom!
GM: The <roll>... fin is cut off the bike, and it <roll>... spins out of control into a tree.
[SFX]: Kabooom!! {trooper flies into a tree}
R2-D2: I guess he had to make a trunk call.
Luke: Yeah. That poor sap.
C-3PO: You can't just leaf him there.
Chewbacca: Indeed. That's a pneumatophore consideration.
{beat}
Luke: Huh?
Chewbacca: <sigh> He was barking up the wrong...
Chewbacca: Tree.