I sugested to put on a Vote kick/ban on the server but admino said that it will not work and probably abused by people.
But there is another way:
I know a server where they have a sort of kick/ban system and this is how it works:

if you type 5 lines in less then 10 sec. it says: next line is kick!
if you type a line then within 10 sec. it kicks you automaticly.

That would be handy for the server when no admins are online