In men, the prostate, which is only for the adventurous or gay male as it can only be tracked down a couple of inches inside the anus (though not ALL men can find theirs this way).
For the adventurous, here's how to (maybe) find it: Take a crap and cut your nails first (advisable), sit in the bath, lube your middle finger with some soap and insert it carefully into the anus about to the 2nd knuckle, then bend it and aim for the back of your dick. Its easier to find if your dick is erect at the time and feels like a small fleshy doughnut. Find the centre. Press. Stimulate it in a rythymic way and its possible to have an arse orgasm!
a spot not only found in the vagina on some females.
in a rare case there are girls who contain their g spot(s) on their neck, earlobes, nipples, wrists, and ankles.