But you can't go into Hogsmeade to spend it. Although I suppose there's owl post.

Longbottom isn't the cleverest or the best at anything magical but the one thing he can usually do very well is be kind to people. The jinx took that away from him. That's why he's so angry at you. If you'd made him look foolish instead of cruel he'd have got over it much faster.

If it bothers you having him cross you could always apologise. Next time jinx him so he grows a walrus moustache, he'd find that annoying in the way I think you meant this one.