A friend at work (K) walked into my office unwrapping a large box of protein/energy bars.
K: Here, I owe you an energy bar.
Me: No you don't. I only gave you one - I've eaten plenty of yours.
K: But it was your last one, it was special.
Me: No it wasn't, I had 3 left.
K: And you only gave me one?
Me: Yeah, so you don't owe me anything.
K: Ok. So do you want one?