Office Attire

Today at work we have a "fix-it" guy wandering around in and out of various offices. He's got a button-down shirt on and I am trying to think of a nice way to to tell him that I am going to need him to button at least three more buttons on his shirt before I will feel comfortable looking at him during a conversation. (the first button is secured just above his belly button... and let's just say he isn't a small guy... his chest is hairless). Any ideas?