Find an artist in your class and have him or her draw something up. Then go to Cafe Press or another type of site to have them apply the design to the shirt.

I would look for a really cool image of a knight to put on the front, maybe a posterization of a photograph of a knight or an illustration. Perhaps you could talk to the art teacher about having a knight designing contest, and having students submit drawings. Stick to flat colors. On the back of the shirt, put a big K made up of the names of everyone in the class, and Kentwood High School Class of 2013 in smaller type. Use a good quality t-shirt, like American Apparel.

Something similar to this would be cool. The best class t-shirts don’t look like a class t-shirt from the front, but look like a really cool ordinary t-shirt.