an undershirt or old article of clothing that is used for cleaning up semen after a sexual act is performed, usually used after masturbation and is commonly located under the bed stiff like a piece of cardboard.
Mom: "I washed that disgusting shirt I found under your bed, was that glue you got on there?"
Teen: "God damn it mom, that was my best cardboard tshirt."
Teen: "God damn it mom, that was my best cardboard tshirt."
by 570 February 24, 2009