The "jam something in its mouth" combat technique works well against a variety of opponents, from giant space monsters to honey badgers to crocodiles.

And if you don't have a handy bone to jam in there, just remember that your fist is full of bones.

Transcript

Rancor: Before we proceed further, I must know something.
Luke: Okay...
Rancor: Are you wearing a rubber suit?
Luke: No. Wait! I mean... maybe?
[SFX]: Grab {Rancor picks Luke up}
Rancor: Let me see. You don't feel rubbery.
Luke: Neither do you. 13.
[SFX]: Jab!
Rancor: Ow! Tha'ssh rearry kwikhe hainphull.
Luke: I attempt to break the grapple.
GM: <sigh> Let me dig out the rules.
Luke: 15.
{beat}
GM: That'll do.