This is a famous joke in south-east Asia (probably spread by sailors) that young girls (highschoolers, etcetera) use to test whether a guy is a virgin.

>Girls have four mouths.
Virgin response:
>What? Wait *counting* there's that hole and ... what?
Sex haver response:
>Oh yeah? Prove it.

So you should observe the main difference between a virgin is that the non-virgin doesn't give a shit.