A Stringy Product on Twisted Orbifold K-theory
  In this paper we define an associative stringy product for the twisted orbifold K-theory of a compact, almost complex orbifold X. This product is defined on the twisted K-theory of the inertia orbifold of X, where the twisting gerbe is assumed to be in the image of the inverse transgression map. 
Alejandro Adem, Yongbin Ruan and Bin Zhang