I have my nick registered on a server and when I go in my friend likes to use my nick and I can't get him off it. When I get on his registered nick I get disconnected and "ghosted" but I can't figure out how to do the same to him. Can someone please tell me how to do this so I can use my nick without worry of what he's said and done on it.

Try asking in a help channel on that specific server.

If by a stroke of luck its DALnet, /nickserv ghost nickname password

Eamonn.

Again, if it's dalnet, use /nickserv set enforce on
That way, he'll be changed to Guestxxxxx if he tries to use your nick.

If it is netgamers try "/msg p set autokill on" to turn on
to turn off "/msg p set autokill off" no " "

after you have authorised,

will kill anyone using your registered nick

and if it's a network like Undernet, with no nickserv, you basically get to fight over nicks http://makeashorterlink.com/?F54521ED9 KeepMyNick is the answer Relies on Notification when your nick exits the server.