Tear up an old sheet to form a bandage that you wrap around your head to hold your jaw shut - or use duct tape if you're bald - or at the very least put your mouse pad on your desk place below your jaw, and watch this video:
Here's The Problem With 1999-2006 Chevrolet GMC Truck STEERING CLUNK!! AND HOW TO FIX!! - YouTube
It's a real YGBFKM moment. At least it was for me.