Can you identify this tool? Not car related--I am 99% sure.

You jam it in the plastic nipple, and the 'teeth' bite into the PVC, then you can back them out - it's for when the nipple breaks off pretty much flush with the threaded joint.

And yeah, I've got a seat wrench or 3 in the garage, too - along with a spud wrench, and some other weird plumbing tools :-)