I understand that the bite test was used by frontier merchants as a low-tech way to assay gold, which worked because elemental gold was softer than some of the less valuable alloys that might otherwise be mistaken for gold.
But Olympic gold medals contain less than 10% gold. They're exactly the type of forgery the bite test is intended to root out. I've even seen athletes breaking their teeth on silver or bronze medals which makes even less sense to me.
Is it all just a big fuck you to the IOC, mocking them for being too cheap to spring for real gold?
At this stage it's a trope that people imitate, perhaps without really thinking about it. Originally it was almost certainly an ironic joke about the value of the medals, playing on the old-fashioned bite tests that would be used for for items of dubious worth