UWE Nikki from Futanaria
As an illustrative example of what I would consider to be an acceptably large penis I present for your inspection busty shemale Nikki of Futanaria whose titanic trouser anaconda of a giant cock I would best describe as rendering her genitalia Unfeasibly Well Endowed or UWE (an acronym which I feel fits the niche quite nicely in giant penis parlance):
