A disparaging term for people who prefer the current 4th edition of dungeons and dragons to 3rd edition, which was current from 2001-2008. It is primarily used on the /tg/ board on 4chan, which is the board that is most related to the game. It is meant to sound similar to "furry," since furries are generally disliked on 4chan. Part of this comes from the inclusion of Dragonborn, a sort of antropomorphic dragon, as a core playable race.
Person 1: I think I prefer 4th edition to 3rd edition, myself.
Person 2: You're such a 4rry. Go fap to a dragon.
Person 1: Have fun with your confusing, impenetrable rules!
Person 3: Both of you can go screw yourselves, because 2nd edition is the best.