This assumes you’re living at home with your parents and they’re not charging you rent.
Learn a programming language (Python or RoR) during the weekdays. Hang with your friends on weeknights.
On weekends, rent somebody’s parents’ Suburban and be an Uber driver in the closest wealthy vacation town.
Take your parents out to dinner once. With the rest of the money, spend half on yourself. Save a quarter of it. Put the rest in Amazon and Facebook stock. Don’t pay attention to the price of the stock for ten years.
Run every other day.
Keep your eye out for somebody special — you’ll know you’ve found the right person when you genuinely want to ask them questions, and not just make conversation. Take them on a date (not a group hang.)
Watch two Charlie Rose episodes a week without looking at your phone.
The week after Labor Day, go on a 10 day vacation some place affordable but interesting. Jet Blue has flights to Cartagena, for example.
When you get back, look for a job and/or build something neat with your newfound programming skills.
Have a bitchin’ summer.