We got the doc out Wednesday in NYC and wanted to get his take on the new craze taking over the social media platform ... where guys are -- we're not kidding -- dipping their testicles into soy sauce to prove whether testes have taste receptors.

You gotta see Dr. Oz's reaction ... it's what you'd expect from any decent human being, especially one with a medical license. In fact, the good doctor dropped some knowledge on us about the dangers of pulling off the stunt. He also clowns whoever came up with the idea.