Power up a Bridgie with the drawbar wrench sitting up there- THWACK! Boy that's hard to loosen!
Crash the carriage of a SB 9 into the chuck and hear the busted off toolholder smack the shop wall 20 yards away.
Did both when I was a young dumb whipper snapper, lived to tell the tale. My shop teacher Mr. Riddle would have chewed my rear.
Certain sounds really catch the shop teachers' ears. My dad commented that he could hear the compound tapping a chuck from 100 yards away. Had enough kids do it, he was like Pavlov's dog hitting the master power switch in the shop.