Yeah it’s always hard to get such varied individuals together. You can get small with it. Maybe the five of you all scored among the top ten in an arcade game. It became tradition to knock each other off the top spot on the weekends. Though unlikely, you became friends through that. You guys hang out in one of the side rooms of the arcade with a few cans of pop and an ice cream sundae or two.
Or maybe you were all friends when you were in kindergarten/elementary school. And even though you all grew into different young people, with different interests, you still carry on that friendship. Though maybe not in school... it draws less jeers if you just hang out in Georgie’s garage/basement instead.
Or maybe it’s as easy as your parents are/were all friends.
Spitballing :D