(noun) One who you excessively visits Myspace.com. Often not doing anything except looking at other people's profiles and/or trying to get people to "pc4pc" (picture comment for picture comment)
Myspace Rats are extremely low on the social ladder.
"Oh em gee guys go comment my new pics I'll totally pc4pc!"
"She's a total Myspace Rat! All she does is comment my pictures saying, "cute pic :D. pc4pc?:)"