In online multiplayer gaming, a smurf is a very experienced player who uses an alternate, low-level account to pretend to be new to the game. People use this strategy in competitive online video games to be placed into a bracket in which they will be superior to other players.
In games like World of Warcraft, a smurf (sometimes referred to as a twink) is a low-level character that is equipped with high-quality gear, supplied by a player's other characters. This gear gives that low-level character increased damage, armor, stats, and health. Consequently, they have an unfair advantage unless they're only competing against other smurfs.
Is smurfing against the rules?
Although creating and playing as a smurf is not against the rules, it is looked down upon in the gaming community. Smurfing ruins the experience for other players, as it's much more difficult or impossible to win against a smurf.