When i was maybe 6 or 7 i had a friend over and my older brother had his friend over, my friend's older brother. They were chasing us around the house and being generally shitbag older brothers so we barricaded ourselves in my room. After about half an hour my friend needed to piss, the toilet (bathroom) door had a slide lock barrel on it but no barrel (presumably my parents had taken it off so we didn't lock ourselves in there). My bright idea was he takes a biro pen in with him and uses that as the lock barrel so our brothers don't barge their way in and terrorise him. It worked great, until he tried to get out and he couldn't get the pen out of the barrel. My next great idea was to squeeze a screwdriver under the door for him to use to smash up the biro. Me and the brothers had all united outside the door by now to help him, knowing if all of this was discovered by my parents we'd all be in the shit somehow. We hear him start chipping at the pen, through tears (he's trapped, claustrophobic and almost at full panic by now), when I hear the sounds of the screwdriver head on the plastic, but, the occasional sound of the screwdriver head on wood. I'm thinking he's going to end up marking the door here and then we'll be in the shit, cue great idea number 3. I yelled through the door for him to put his other hand around the lock bracket to protect the wood, he does so, and ten seconds later he's impaled his hand with the screwdriver.
Long story short my dad had to break the door down, we all got in the shit and to this day my friend never locks doors with biros.