KICK HIS ASS!! I'm just kidding.. Confront him and be honest about this. Tell him that it was wrong and that it's your money. If he refuse, ask why he's lying, stealing etc.. Otherwise, try violence or police.
All right now, son, I want you to get a good night's rest. And remember, I could murder you while you sleep.
Hey son, I bought you a puppy today after work. But then I killed it and ate it! Hahah, I´m just kidding. I would never buy you a puppy.
"Three witches watch three Swatch watches. Which witch watch which Swatch watch?"
"Three switched witches watch three Swatch watch switches. Which switched witch watch which Swatch watch switch?."