In men there is a tube(for a lack of a better word) that runs from the base of the balls straight up through the tip of the penis, this is the tube that carries the cum.
If you apply enough presure to that tube when you are about to cum you can stop it. THIS IS NOT A BIRTH CONTROL METHOD! Thus making you last longer. try it the next time you materbate. i learned this from a wiccan book on sex majic.
gate