WordPress MU

I have searched the forums already, without success.

Let's say you want to prevent users from creating blogs with certain blog names.

Let's say you want to exclude certain words, maybe curse words, or whatever... Is it a standard functionality?
Is there a plugin, something?

If not, where would you start?

No plugin necessary. Go to Site Admin > Opitons > Banned Names

God, feel stupid now. It is so easy.