I use these reusable coupons for motivation in the classroom. You could sell them in a "class store" or you can give them away in the class for outstanding effort, participation or any other reason you can think of that motivates your students.
This coupon entitles my students to wear their PJ's to school. I only let them "cash in" this coupon on Fridays.
I had 6th graders and they LOVED the coupons!