With this patch I've noticed that doing /dance while in an attack stance does not cancel the attack animation. This causes your lower body to dance while the top half stays in attack stance.
YouTube - Dancing Glitch 4.0.3a
Or in case you're too lazy to click the video...
Step 1: Right click something you are capable of attacking. Do not be in range to attack it.
Step 2: /dance while in the fighting stance
Step 3: Watch as you and everyone around you laughs like hell depending on what race you are.