Also known as "Picture Comment For Picture Comment". Usually used on large Social Networks like MySpace, Bebo, and Facebook. "PC4PC" is a way for extremely fat and overweight teenage girls to tell all of their friends (friends as in people these fat overweight teenage girls go out and request everyone, even people they don't know as friends) that they have another 100 of the same pictures of them just as different angles uploaded, and they want other fat overweight teenage girls to comment on their pictures, so they don't feel ugly, so they want their "friends" to comment and say nice things on their pictures... And in return the fat overweight teenage girl will comment on the other fat overweight teenage girl's pictures telling her she is pretty too.
Fat Overweight Teenage Llama: "PC4PC ON MY NEW DEFAULT."
Fat Overweight Teenage Emo: "You Are Like So Pretty, I Wish I Was As Pretty As You!"
Fat Overweight Teenage Llama: "Oh Em Gee! Me Too, Don't Say That You Are So Much Prettier Than Me, I Wish I Was At Fat And Overweight As You!"