Ahh, that could be it. I had his balls removed when he was pretty young because my mother didn't want him pissing around the house stinking it up.
He's actually a very good cat in that department, he'll just meow by the back door whenever he needs to go to toilet or just plain bored. In the past 3 months he hasn't used his litter tray once. Which is saving us a bit of cash now that we don't have to buy him litter.
I don't let my cats outside because it's too urban here and they would no doubt get hit by a car or something easily. I also don't want them bringing flees in.
It's not like their bored or anything, they are actually pretty happy cats. My apartment/house is big enough for them to run around in and stuff.