I constantly type /sigh in game, only to be /disappointed when it gives me an error.

/sigh

I'd expect the shoulders to go up and down, the toon to slump a bit, and maybe add in a slight headshake.

For variations, I draw inspiration from my experience teaching teenagers...big inhale, exaggerated exhale, gaze at ceiling seeking help from divine sources. Or do the sigh and then put one hand over the face in despair (other hand tucked under elbow/wrapped around ribs). Or rub eyebrows/bridge of nose. I have done all of these, sometimes several times in a row. XD Bonus points if you've got a 'Why God why' expression. They think it's hilarious.