Here's a new one to me, and I've legitimately had or been around easily 2000+ disassembled engines. Not going to say what kind of car/suv/truck this is, but it was less than a week old. Owner said they heard a loud "ca-thunk" and then the engine wouldn't turn over...... I figure the valve had to have broken while the piston was at BDC and was just starting it's up stroke, flipped a damnnear perfect 180, and Mister Piston proceeded to impale himself with the stem like a nail on the first try. Funny thing was it was holding coolant on top of the piston and not leaking a single drop down. Wiped up the coolant to discover this, and not a mark on anything, but the valve ain't coming out of it's new home. It's that stuck....kinda cool.