Autocorrection

I once did this to my friend's laptop at university. Unfortunately I also completely forgot that I had done so, so never told them.

I received phone call at around 1am that morning. Credit to my friend's comedic timing, she didn't just come out with "you jerk, change it back". She instead very calmly and meticulously provided context to the story (it didn't click at this point) then, with a hint of bewilderment in her voice, described the phrases that were appearing on her screen as if it was at once completely normal yet strangely inexplicable... just to see how long I could hold out before laughing.

As soon as the penny dropped, I cracked. I sheepishly marched over and changed it back.