"Hey buddy, can you do me a favour?"
"What do you need?"
"I haven't eaten in like four days, and I'm a couple bucks short of getting a large pizza. Can you help me out?"
(pause)
"I don't have any cash, but here, take this"
(reach into bag and pull out an apple fritter)
"Oh." (pause) "Thanks man, but I can't - I'm allergic to bread products."