That sucks especially in the week before Christmas! Instead of taking money from him, could you explain to him what has happened and that you have to pay for it and that you would like him to help pay for it and talk to him about doing some extra jobs at home to earn some money to help pay for the bouncer. I wouldn't take his present money away from him, but get him to 'earn' extra money to help pay for it.

It is so frustrating when stuff like that happens.