I'm glad you're not trying to get this guy in trouble. I wasn't sure when I read the first post if there would be a flood of 'Tell your supervisor and get him fired', but I'm glad there's not. Everyone has a sense of humor, it rocks
Edit: And I think you should have found another photo of some guy's genitals and changed it to that. He'd know you saw his original icon, and then he'll be freaked out forever wondering if it's yours.