Got a celebration like Prom, Homecoming or Snow-Daze (that's the Up-North version of "homecoming" surrounding a hockey game) sell a souvenir!
There are "T" Shirts, Sweat Shirts, Cups, Buttons, Pom-Pon's, Giant Foam Finger, stadium cushions, Sports Calanders, the list is endless. Just remember, anything that needs a design, like a button or "T" shirt - have someone in your school create the art work!
Be very careful with any type of special event product, once the event is over you're not going to sell anymore! I mean that homecoming giant foam finger was "pretty cool" I mean "number one" at the Friday Night Game but, yeah, not so much on Monday morning at school. You'll be stuck with them - order less than what you thing - high demand = quick sales!