A black floral long sleeve shirt and dark green shorts worn together are a match made in heaven for gents who prefer casual looks. You can take a more relaxed approach with shoes and choose a pair of sandals. This getup is most probably exactly what you've been looking for as a teenage guy.
Dark Green Shorts with Sandals Outfits For Men In Their Teens
Team a brown print short sleeve shirt with dark green shorts for a laid-back outfit with a clear fashion twist. Play down your look with a pair of sandals. Gents who are curious how to wear modern off-duty style as you are making it through your teenage years, this combination should answer your question.