How Could I Be So Stupid/Careless?

In the early 70's my first Mopar was a 69 383 4 speed RR. I had bought a 'pizza pie' air filter which is a big flat thing with a thin (useless) foam filter and perforated cover on top. The stud is VERY short, and not visible, as you put the base/ stud together, then lay in the foam, perforated piece, and a huge floppy snap ring.

I was sitting in traffic and absent mindedly blipped the throttle when it "stuck on fast idle." I kicked it a couple of times, and the idle came back down. Seconds later, a valve ate the stud

Believe it or not, did not seem to hurt the valve. Pulled one head and replaced that piston.