Suffix, common on *chan type sites and some other internet forums; roughly synonymous with person.
As used on
4chan, not always derogatory. They label may be self applied, as in the
case of newfag or oldfag to indicate either humility or pride, depending on usage.
Sometimes the uses are derogatory, as in the
case of moralfag, someone who is worried about the morality of a certain action.