I had mine cut on the 16th birthday solo. It was still hanging up years later, but I doubt it still there after 25 years! When I instructed I told each student about the tradition and gave them the option of doing it, so they could be prepared with a T-shirt that I could cut and decorate. I hung them up for awhile and let them take it when done with their training. I got really excited when I soloed someone. They got the T-shirt cut and a certificate. One school even had a Polaroid camera to take a photo in front of their solo plane. That was cool too.
It kind of makes me want to instruct again- part time. I have 1600 dual given in GA aircraft and 2595 dual given/checkairman in a jet. Too bad my certificates are expired!