One day a coworker of mine was walking into our huge office building and thought he saw a mitten on the ground of the lobby. When he picked it up it was actually a pair of lacy women's underwear. Ostensibly it fell out of someone's gym bag or got caught in their pant leg in the laundry and dislodged there. He drops it immediately and comes into the office. He doesn't mention this to anyone.

Two hours later the main receptionist comes in with the underwear in front of our whole group and says she saw him drop these this morning and she wants to return them. He's denying the whole thing and at this point none of us have the previous context and all locked in to the conversation and silent laughing. She says, "We just want to give these back in case they have sentimental value!" and the the whole group is dying laughing now. He eventually convinces her he isn't interested in a stranger's underwear (which she bare handing) to which she says she'll keep them in case he changes his mind (???).

It's been 5 years and it gets brought up nearly daily