May I add a non-money related one?
Coworker sees me pouring in my coffee milk from a recycled juice bottle, inquires about it, and I explain him I ain't drinking that dairy-fluff stuff they give for free, because it's not actual milk and I prefer knowing what I drink. He looks conspiratorially at me and asks me "Is it your own milk?". The guy next to me almost spit his coffee. (And no, I'm not lactating)