"Found money must be spent"

Or at least that's what my mom would have said. I made a little money today, by taking a survey, and it was burning a hole in my wallet. Well, I could get a new pair of tennis shoes, which I needed, a nice bottle of wine, which I wanted, or I could get my son some shorts and pants that he really needed, and some hot wheels for all of them, and pay the "party money fee" the school is asking for us to send. On what did I spend my found money? The shorts, the hot wheels.