i have 4 pack abs, very little fat, and moderate sized cut arms and an adult chest. If you saw my torso, you would definitely not think i'm a teenager. When i look at some flat chested guys by the pool trying to get with some women, the women usually look over at me and i feel like going over there and stealing her from him. But i know once i get within 6 feet, she will be able to see that my frontal hair is pretty darn thin, at least 1 inch from the hairline.
but i also have a pronounced frown line between my eyebrows, a redish tint to my face, and a minor hunch back, which make me look older and less fit. I'm working on it.