I find it odd that her very first assumption is that he's a prostitute. I mean for all she...

I find it odd that her very first assumption is that he's a prostitute. I mean for all she knows it could have been an older relative that's giving him money to help him get through university. Also wouldn't it have been easier to just show ID to prove that he's only 20 instead of punching a guy? Oh, and everyone in that school who believes the rumour sucks.