Everyone loves a play on words - even cats.
This is another play on words to capture the customer's attention.
In addition to an image or depiction of an activity (guitar playing, racing, etc), these shirts often use a pun or play on words and a touch of humor to add interest.
You may also want to look at how you might be able to create a play on words that have to do with your school team name.
For example, Pringles used a play on words of Devo's Whip It to promote their potato chips.