If a girl is all like "ooh flex for me"...half of the time I'll do it. It's not as if I'm doing something difficult or running around saying "I've got massive 13.5 inch guns, they're hyoooooge". I flex. No biggie. If you wish to call it "show boating" or whatever, I agree to an extent. However, I'm not ashamed of it. I do it only when asked, or when I'm joking around. I'm not the kind of guy who turns my tee into a tanktop and walks around flexing. Generally I like my long sleeve shirts anyways...