I had a boss a few decades back that used to give me another task or two every time we passed in the halls. Being already overloaded, I wasn't very appreciative.

I started saving all of my questions for him until these pass-by's. I started giving him so much more stuff, that he began seeing me coming and would jokingly say "Oh, piss off!"

I later heard of another colleague who would answer an additional job request with the question "Okay, what DON'T you want me to do?"