How about the strangest, weirdest or more stupid modifications you made to your Pontiacs as a kid.
I was a tinkerer .... I hooked up an electric antenna motor to my glove box door. Used the driven nylon core of the antenna to open and close the glove box door. I could make it open and close real quick like a berserk giant clam.
I installed a home 8-track stereo under the dash. Bypassed the AC transformer and ran it on the straight 12v DC from the battery ... and it did work for a while.
I removed the front wheel wells cause I thought it would look cool ... it did make working on the exhaust manifolds and changing plugs easier ... but the battery fell out once.