You see: You chuckle. Others see: <Player> chuckles.
CHUCKLE <self> You see: You chuckle to yourself. Target sees: <Player> chuckles to <him/her>self.
CHUCKLE <player> You see: You chuckle at <Player>. Target sees: <Player> chuckles at you! Others see: <Player1> chuckles at <Player2>.