Ah yes. Never a dull moment.
My favorite had to have been the high school kid in Kyoto some years back with a T shirt that just said, "ALABAMA: TO BE FAGGOT". He hadn't a clue what it meant (neither did I).
The girl on the Yamanote train line with a "Shit" backpack was curious, too.....
Not just t-shirts - I vividly recall attending the visiting American Ballet Theater in Meiji Jingu in Tokyo...very, very expensively dressed lady in front of me, with a bolero hat and a sequined jacket that spelled out, in all its glory "Who the F*ck Needs Art?"
I cannot imagine what she paid for it, but you know Tokyo prices...
You should see the F*ckers line of clothing that my students wear to school...