Today is my birthday, and a co-worker brought me a small cake. I figured I'd share with my fellow administrative assistants, so we'd cut the cake and had put the lid back on, and it was on my desk.
A professor wandered through our office, said "Oh, hey, cake!", lifted the lid, cut two huge pieces and said "I'm not going to eat it, but I'll take my kids some.." and walked off.
We were all kind of speechless about it. This professor always does stuff like that. She will take half of a leftover pizza for her kids, big chunks of cake, cookies, and so on, all without asking or being invited to take any.