One of my co-workers is a big time deer hunter (took his first deer at age 8) but had never fired a handgun. I took him to the range, tacked up a paper plate, stepped back about 7 yards, and put my 642 in his hand. He fired 5 shots, and there wasn't a mark on the plate. He said, "You put blanks in it!" I told him to load it himself and try it again. He did, and again, there was not a mark on the plate. I reloaded, gave the gun to my son (who was 11 at the time) and he put all 5 onto the plate in a group about the size of my hand.
My friend was staring open mouthed when my son, with all the innocence and sincerity of youth, turned to him and calmly said, "You were doing it wrong."
Since then, anytime someone does something stupid here at work, we say "You were doing it wrong."