This pairing of a harrington jacket and a tan crew-neck t-shirt is irrefutable proof that a safe off-duty ensemble can still be truly stylish. Complement this look with a pair of brown leather sandals to keep the getup fresh. This combination isn't a hard one to score and it's summer-appropriate, which is most important when it's roasting hot outside. As you can see, as a 20-year-old guy, you have a wide range of sartorial options.