SUBREDDIT: r/tifu
TITLE: TIFU by locking a friend's cellphone
POST: This happenned about thirty minutes ago, so it's a legit TIFU (yay!)
I was having dinner in the dorm where I live with my dorm companions, and while one of the girl goes out for a moment, I start playing with the lock screen of her phone. First I was thinking of the usual "Hey, you wana use your phone? Well you can't for 1 minute!" joke, but these phone would only make you wait ten seconds and let you put the password again. It's one of those "pattern" locks, so I started doing symbols for fun. I forgot about what would happen if you play too much with that... Black screen, answer your secret question or input your Google e-mail. "Whoops. She'll have to use the recovery mail". She comes back, I say what happenned and she suddenly turns white, literally. "Oh my god. What have you done. Oh my God!". Here I am, she sleeps next door, and I'm hearing an argument between a girl and her father about why she doesn't know her Gmail account and the fact that they will probably have to reset the phone. The worst part is that I know 3 ways for her to recover the lock without losses, but she is utterly mad at me and doesn't want to even come near.

Sorry if I wrote something wrongly, English is not my first language.
TL;DR: 
Played too much with the lock screen of a friend's phone, got her to argue with her dad and she will probably have to reset it.