Actually, it was an alert() box plus evil.js, which overwrites lots of native JS functionality to intentionally cause weird bugs. The idea is to make it imposs

Actually, it was an alert() box plus evil.js, which overwrites lots of native JS functionality to intentionally cause weird bugs. The idea is to make it impossible to ignore so abusers will stop their hotlinking. I'm not really interested in shaming anyone, though. I think it's usually just a simple mistake where someone was lazy and didn't bother reading all the caveats.