Reddit, what's the meanest thing you've ever done to a complete stranger?

Here's mine- a few years ago I was in living in college accommodation. My room mates and I were somehow so lacking in knives and forks to the point where there was one fork which we all shared. So one night me and female room mate were watching a movie. She fell asleep like 20 minutes in and shortly afterwards there came a knock on the door. I opened up and there before me stood a complete stranger. She explained that she lived upstairs and was having a party and was saying we could go if we liked. I was about to decline but I suddenly thought of the k.u.s.c. (kitchen utensil shortage crisis) and then agreed to go. Whilst putting on my shoes I considered the morality of what I was doing and then thought about the possibility of making new friends with people at the party. This led me to question my plan. Then I found myself in the elevator with the girl and her friends heading up to her apartment. Once I'd heard and seen how obnoxious, rude and unattractive they were, I was already fantasising about the adulation that I was sure to receive from my room mates upon returning with my stainless steel treasure. As soon as we got up there they went to the balcony for a smoke, I went to the kitchen to get "a drink of water", and when I say "drink of water" I mean 3 knives 4 forks and 2 tea spoons. I promptly left and received many a high five from my room mates.

I know I write this as a funny story but lets face it, a girl tries to be a friendly neighbour by inviting me to a party and I respond by going to her apartment and robbing her? That's pretty god damn mean. I do not, however, regret it. Anyways this seems like something we never discuss; we've often talked about mean stuff we've bore witness to but I think more than a few redditors are guilty of being bastards to complete strangers for no good reason. So let's hear your stories!

TLDR; friendly neighbour whom I didn't know invited me to her party so I robbed her cutlery.