Looking for a yes or no on this one, here's the back story. My son was invited to an event and my wife and I gave him $40 for expenses. When he got back he still had the $40 and he said the other family paid his way for his birthday next week. For the record $40 is no burden to either family. One of us thinks my son should keep the money since we planned to spend it on him anyway. The other thinks we should keep it as the expense wasn't as expected. So what do you think?