Local high school football games are Friday nights, too. Swim meets and volleyball games are also exciting, with minimal cost. You can also get involved in an extracurricular sport at your school. School clubs are a fun way to meet people. You all share a common interest, and there are a lot to choose from.
Community service is also an option.
Talking to the elderly, helping out at the hospital, volunteering at a camp, or even tutoring a younger sibling or friend are some good ways to help the community. You can also ask your neighbors if they need a baby-sitter on Saturday night, or you can mow your grandparents' lawn. The opportunity to serve is always there. If all else fails, have some people over to your house to watch a movie. It usually only requires three bucks for a video, a bag of chips, a 6-pack of soda, and a couch.