Just in case someone might consider it griefing, which they totally shouldn't in the context of Glitch, this should at least confer the same bonuses mourning or celebrating confer. Or, if it's something you can do on top (heh-heh) of celebrating or mourning, perhaps it would give a monetary bonus to the dead. "Walruz danced on your grave, and you get all the tips! 250c!"
Interesting idea, and would be funny :P Though not of importance, and what would it do? Like Carl said, maybe give currants to the person? Only one dancer per grave, and a small chance (1/4?) of getting currants/rewards (the dead person).
Either mourn/celebrate of danced on, not both? Mourn/Celebrate is a Diabolical Drink Ticket, while the Dance On is a chance of currants/rewards?
I would see people complaining about the ethics about this though and how it would offend some people.
If it does the same as mourn or celebrate, and just gives a different message and set of flowers, then I think the flowers should be rainbow colored! You know, all festive and stuff! Or sparkly like a disco ball.
I think "dance on" would have to send mood or iMG to the person belonging to the stone. I want to dance better than my butler, though. Can we then also "zombie" on a grave, providing us with mood or iMG?