I got this shirt when I went to visit MIT in 2000. I liked it because it was quirky and had equations on it. It wasn't until my Sophomore year when I found out these were Maxwell's Equations. It was such as awesome epiphany when I realized the equations we were studying in class were on my shirt. I love this shirt, but it became ridden with holes after all these years and it had to go.
The equations show how electricity and magnetism are related.