Why is he being like this?!!?

I don't understand why your BF is being this way. Your right that it does seem immature, and quite paculiar. In my opinion, it seems a stupid thing to get angry over. You won that bingo money, and you should keep it. It seems quite rude for him to demand ou split the money. I think he's being a whiny baby. The only thing you can do, however, is ask him why he wants to split it, and maybe there is a legitimate reason for it. But i highly doubt it. Ask anyways, because its better to know than be kept in mystery :)