Oh, the stupidity

[ZiNgA BuRgA]

I find it highly amusing:
http://mybbrunway.com/forums/thread-mytips

Ignoring the fact that the second code given isn't even valid HTML, they don't seem to get it even if the problem is basically thrown at them in the face.

Oh well, most MyBB community members are stupid, there's nothing new about that.
But if you do see anyone use something like that on your forum, you can have a field day with XSS exploiting them (psst, I bet the OP has it installed on his forum, if you want to mess some thing up, gaining admin access to his forum might be fun - that might teach him to actually care about security issues reported to him and maybe think twice about not giving clueless people exploitable code).