Also, sperm do not have a vagina-homing device so if they land on a park bench or a leg or something they're not going to sprout legs and crawl to the nearest vagina. :-)
Well, I personally always lug a park bench into the shower with me, I think it adds to the fun enormously. Especially the bit where you have to break down a wall.
(My new icon is in honour of all those people who were raving on about the cuteness of penguins a few days ago and wanting to keep one in the bath. And the one or two people who have read the book it's the cover picture from, namely Death and the Penguin. I would like to make it clear that while this novel features a penguin called Misha who is sometimes in the bathtub, as well as Russian mafiosi, at no point does anyone climb into the tub with the penguin, mafioso or not.)