He Missed Head Day
This guy's body appears oddly proportioned. It seems like he works out every muscle to increase its size, but he consistently neglects training his neck.
In reality, it appears that his body was artificially widened through image manipulation, and they forgot to adjust the proportions of his head. However, don't blame the guy; he was merely the model for this photo. Asos, the company that ran this advertisement, made a real mistake.