I think in my case it's down to the fact that I had some Hypospadias surgery when I was younger and there was a very strong emphasis on peeing correctly. Whether or not it was connected with the surgery or not, I've always had a small penis, so envy of, and fascination about, guys with much bigger endowments was, I suppose, natural. Thanks to a shocking programme called Eurotrash, I learned around 1999 about Jonah Falcon who is claimed to have the world's biggest functioning penis. Inevitably the programme centred exclusively on his sexual prowess. However I ended up masturbating for much of that night, thinking about him needing to go to the toilet and wondering what it was like like to pee with. Then I discovered LPSG and my fascination, though urinary rather than sexual, just grew.