I'm bi so...maybe not your target audience with this question. Personally, while boobs are great, the genitals of neither sex are really something I want to see randomly in messages without warning. A penis is great for practical purposes but its not like I want a sculpture of one sitting on my coffee table. Same thing with a vag. If I'm already in the mood and you're my partner then sure - sexy as hell. But really, no, not very exciting to just randomly see one without invitation.