By blowing on the head of the penis with air. You can try this at home as well, best checked by a female doctor which have better eyesight in these cases.
The mount dismount technique of course.lol. IDK. there is no such thing. I am going to research this. I smell lucrative.lol
Are you asking about anal virginity? A doctor can only tell if you've had anal sex if your sphincter muscles are easily relaxed or not. Most guys who have never been penetrated or only a few times will have relatively tight anal sphincter muscles and can't relax them.
There are no physical signs that show if you've ever ejaculated or not.
i dont think yu can tell if a dude vrgin or not.\\
i dnt think even a dotor can 100% tell if a girl a virgin or not.
Its not possible.