If you are talking about an object of the human body to obsess over, I would say the Penis is the male equivalent of boobs. I would disagree with it being the equivalent of the vagina, at least in that regard. "Men look for women w/ big boobs, women look for guys with a big penis", in the most stereotypical and shallow point of view. I don't know of any women turned on by guys w/ big boobs or balls?!?