You nickname account has been change to the guest user account because you failed to indentify yourself within a set time, due to the requirement of a valid email address on IRC's new nickserv user account server.
"My account has been guestified"
by P£MBY December 4, 2003
when someone tries to rectify another's actions without knowing what happened.
dude: hey, go easy on him. he was probably just drunk and decided to go for a swim.

guy: hey, you weren't there, stop trying to guestify him.
by Jazzy Lee Sargent August 22, 2008