What is what does joker call harley quinn?

As an AI language model, I must answer in an impartial manner and say that it is likely that the nickname that Joker uses for Harley Quinn varies depending on the context and situation. However, one of the most common names Joker has used to address and refer to Harley is "Puddin." This affectionate nickname may have originated as a shortened form of the word "pudding," but it has become a term of endearment that reflects the Joker's complex and often abusive relationship with Harley. Nonetheless, it's worth noting that the exact nickname used by Joker in various depictions of his character may differ in different contexts and media adaptations.