you know, people have done weirder stuff. This isn't just the sort of thing one throws up out of frustration or because they're having a bad hair day. PMS is not an affirmative defense for this kind of thing. This is the kind of stuff that is intended to insult and hurt. People usually don't intend to do harm unless they're mad about something.
So, it's not such a bizarre assumption at all. Especially when you consider just how obnoxious somepeople can get when they've been drinking, like this couple was.
I don't pretend to have been a fly on the wall, but it strikes me as curious that someone did this without being provoked somehow.
Next?