I think this recipe book implies that you get your semen from an animal source other than human. The first post said they purchased theirs from a pig farm. Its not much different than eating rocky mountain oysters in the weird factor I would guess.
Still not sure I'd try it, but damn it was good for a laugh. I'm tempted to freak im2smrt4u out by chasing him down with a measuring cup, telling him I need his semen for a recipe.