FYI, it could be because the game doesn't notify you loudly when you have picked it up.
To get the shirt:
[*]Go to the photobooth
[*]Go to the end of the room (with no other clothes on other than the default)
[*]Walk off the floor three times
[*]The third time you'll be upside-down. Run to door when you are upside down
[*]Keep moving around until you see a gray "tattoo" on him
You will have the shirt. It will pick a random line from the game to tell you that you have received it. The line will be incredibly quiet.