I agree that it should be called something in line with the characters and theme of the story.  For instance, if it's a magical world maybe Lustful Wand   . 
But I kind of stick with member, cock, dick, monster yada yada yada.  Playgirl did have an article quite some time ago that had a whole list of names like Pike of Love, Horn o' plenty, monster muscle, and Kingpin amoung others. 
I say just use what you think is right, if after you've read through your story and you're happy with the amount of times you've used a certain word then go with it.  Sometimes I think people aren't happy unless they have something to bitch about. 
Good luck.