Need help......as of yesterday morning when driving and I hit a bump or turn I started hearing this fricken noise like something moving around in the rear of the car.

I took all my crap out of my trunk. and starting eliminating what it could be.
After a while I tapped on the muffler with my sneaker and noticed it had some play. So I moved it a bit more with my hand ( to recreate car on the road scenerio ) I heard the same noise............

Wtf can it be? Do I have to get one of the hingers re-welded or something?