Important Legal Question!

[Truefaith87]

The Manderville Dance is the copyrighted material owned by Square-Enix and whatever parent corp. Accordingly, they have rights in derivative works, displays, yada yada.. all that good stuff found in § 106 of the Copyright laws. Such a shirt would undeniably be considered a derivative work. The moment you start selling it, SE has every right to send a cease and desist letter to your house. Whether they do or not is another story (see Etsy which seems to be built on copyright infringement :P ).

(additionally, you're arguably prohibited from arranging a flash mob to perform the Manderville )

To cut the answer short, I have no intention of selling one. I intend to make one for myself, and only myself. Most likely not even use a character or even model from ingame, simply a shadow silhouette showing the motions to follow for the dance maybe a few other details about it.