Here’s a homemade one I used to wear until I wore it out:
Image of the planet Earth with cracks and a bolt coming out the front of it and a nut threaded onto it.
Text: “The world is held together by nuts under tension. MENTAL PATIENTS’ LIBERATION FRONT”
A guy I work with has a T-shirt that says “Boy Kicks Girl” with an accompanying stick figure. He says it’s the name of a local band. I don’t think I’d want to wear that T-shirt.
I like to wear my blasphemous Skeptic’s Annotated Bible T-shirt. The irony, of course, is that it’s just a Bible verse on the back.