Not sure how, but judging from the precision, it appeared that someone on a train tried to cut a back pocket on my jeans. Not like I carry a wallet there. If it was a rip, it was perfectly clean...but either way, a large portion of my butt cheek was exposed on my way to work. I didn't even realize until probably an hour in the office.
Thankfully it was me and 1 other person in the office that day. I found a pair of yoga pants in my desk and she stood guard at the door to make sure no one walked in while I was changing.
We still have a good laugh about that.