A white long sleeve shirt and black chinos are the kind of a never-failing off-duty look that you so awfully need when you have no time to craft an ensemble. Add slip-on sneakers to the mix and the whole ensemble will come together perfectly. When it's one of those gloomy fall days, sometimes only a neat getup like this one can get you out the door in the morning. And if we're talking outfit ideas for teen guys, this ensemble is perfect.