This one is funny and a bit geeky:
Here's one that plays with the "God particle" concept:
Higgs Boson Is My Co Pilot Particle Physics Humor Tee Shirts by greenbaby
Here's a pun on the word "mass", connecting religion and science:
This one has a nice illustration on it:
This equation is the Standard Model of particle physics. Fair warning: I wouldn't wear this one unless I could explain it. Just sayin':
"A Vote For Higgs-Boson Is A Vote For God." This one is probably made by a non-physics major, but still.