I'm alone in my office. A guy I've never seen before just popped his head in and said, "Just checking to make sure you're still here!" in a way that very much implied he knew me and wanted to check on me, specifically. He started to leave, then turned around and asked if I had any bottle caps. When I said no, his tone turned conspiratorial and he said, "I'll come back and tell you how to make money with them!" And then he left.
UPDATE: I'm home safe now. Didn't mean to freak everyone out! He seemed pretty harmless, really, though of course you never know.