Do you why Olympics athletes bite their medals? Not because it is made out of chocolate or get a chipped tooth – that will be a huge bill on their dentist bill, but they could pay it off with the earnings that they made with their medals they won. The athletes do get paid for their performances.
In 1912, the gold medals were solid gold, so gold was a soft metal and when you bite into it, it will leave a bite mark on the medal. It was way for the athletes to know it was real gold and the dentist bill that came along with.
It was a tradition for a long time; most athletes do not know why they are biting their medals and the photographers ask them to take a picture biting their medals.