Yes, its a hacker. This has been going on for sometime now.
Admins had already banned this guy, but he seems to come back after just a few minutes, with a different ID. Im guessing hes using proxy, so its not easy to get rid of him completely. I might be wrong with the proxy thing, just my opinion. But this im certain, its the same guy doing this over and over again.
Here r some IDs which he used : Negrophobic, handsup, !surrender, AustLnpower, [AE]rox.and many more. He was there once when admin areox was online, and he banned him, then he came back with the ID [AE]rox, just to piss areox off.