A denim jacket and a beige sweater vest are an easy way to inject a dash of masculine refinement into your casual arsenal. You can get a bit experimental on the shoe front and dial down your getup by slipping into black leather boat shoes. Clearly, it's easier to work through a hot summer afternoon in a light and breezy ensemble such as this one. Definitely a wonderful option when it comes to outfit ideas for 20-year-old men.