My child has bypassed the lock screen on my laptop and caused a gray-screen-of-death, just by banging on the keyboard. I saw it, I am unable to replicate it. Everything should be tested by a child before it can enter production service.
My kid subscribed me to Apple Music by playing with the apple tv remote...
I know exactly what you mean - from toggling a mode on a mechanical keyboard I didn't know existed and spent 20min looking for how to turn it off, to managing to delete several Powerpoint slides that were not on the screen at all, solely via keyboard (so that I didn't notice it until saving/closing the file and losing them forever). It's amazing :)
I recall a kids game where the game exited when the spacebar was touched. It was pretty exasperating, because the kiddies couldn't figure out how to get the game running again.
Human-powered fuzzing! As a parent of three kids under 6, I wholeheartedly endorse this.