Ecstazy, I could understand that you teamkilled your clanmates/friends, but, even if you find it funny, the people, who are not your friends, that you teamkill, don't find it funny.
If someone you don't know suddenly teamkilled you for no reason, I'm sure you would be posting a ban request as well.
The ban duration escalates with your ban history. If you keep attacking teammates, you will be banned for longer, and, eventually, for good.