Greek is supposed to be taboo a no-no but a lot of people like it because it supposed to be "exit only" and people enjoy/get turned on by things they aren't supposed to like or have been told were no-no's,  fetishes though something are usually taboo things as well..... in this case with golden showers/watersports he could get aroused by the warm feeling of the pee, the aroma of it, taste even, the fact that you're using him as a toilet and you're subjugating him to something that's supposed to be filthy turns him on...I could go on lol.