i've never caught anyone really ****ing with my bike. once i caught a guy trying to take my fender when i came out from a building to unlock my bike, and i was just like "excuse me sir" and unlocked my bike and rode off like nothing happened.

but people do some ****ed up **** to my bike. once, someone twisted my stem nearly 180 degrees (well, as far as the bars can turn) so my handlebars were insanely crooked. i left my tool at home that day, so riding home was a mission.