A T-shirt with a comic from The Far Side on it. The cartoon shows a young boy student pushing on a door to get into a school called Midvale School for the Gifted. The door is labelled "pull". (Picture here.) Fun fact: I wore this T-shirt to actual gifted school. No one said anything about it.
A Looney Tunes T-shirt with Marvin the Martian on it surrounded by much larger aliens while pointing in a direction and saying, "Bring back my Aludium Q-36 Space Modulator!". My mother said it was so me, but I mostly don't get it.
My mother gave me a hemp tie-dyed T-shirt with a mustard stain on it. It was stolen when I left it in the laundry.
I got a T-shirt at Zellers (now out of business) with a portrait of The Thinker by Auguste Rodin. It also had the text "I THINK", and in smaller letters, "therefore we have nothing in common". My mother said to me twice, "Not many people can wear that, and have it be true.". This T-shirt was popular with others, I got two compliments on it.
Side note: I used to go to Linux users group meetings. I kept winning T-shirts there as the door prize, but I kept only wearing a Debian T-shirt, which I had not bought there. As a result they held a vote and banned me from winning more T-shirts there. I lost out on one T-shirt because of this.