I don't understand why people saying it is her elbow as she is wearing clothing that covers her elbow. I still think it's a prosthetic due to the lack of scrotum. It's the type of thing TOWIE would do to get people talking 
But her dress is black and that is a dark skin colourI'd say it's the elbow of her dress.
That's what I thought, some sort of lengthening thingit's a cock sock. Watch it in hi def and you'll see he's wearing something over it.