LOL....As the above post says, Arginine is known for helping with erections. It helps the body transport more fluid(cant remember the name) to the penis, which can result in longer lasting erections..
It's also said that a large amounts of Arginine can produce GH increase, but the results of that are inconclusive. If I were you, just stick with a good whey protein that has all the BCAA's, including doses of Arginine and you'll be fine. Unless of course you're going after a longer lasting "boner"