Put a little twist on your average game and get some half-time performers. The act(s) of choice could be a locally-known band, your school’s dance team or cheerleading squad, or some students with unique talents.
People who don't play basketball should still have a way to participate and help out.
You (or if you're shy, an entertaining Master of Ceremonies) should be making annoucements about the cause everyone is helping.
Welcome people, say hello at half time, and thank them at the end of the game.
Mention where the donations are going and how it will help.
Give numbers! How many people will the donations be helping? What is the goal that they need to help you reach?
Where it all goes
Make sure to set up just which food bank, shelter, or organization will be picking up or receiving these donations.