So say there's two kids, or adults, and one person takes out a piece of gum and starts chewing it.

Person 2 asks if they can have a piece of gum but Person 1 says "That was the last piece", even though he or she has another piece.

Person 2 then says something like "please..." or "I don't believe you, show me" or "are you sure?" or "I saw that you have more".

Who is being rude here? Person 1 that doesn't want to share but is trying to be nicer than saying "no", or person 2 who is pressing for it not for sure if they have some or not.