My first ever experience on this. It was pretty awesome, not what I expected - better, I think. There is something quite erotic about it.
There is also a HUGE amount of trust that plays in here, at least for me. Despite being a public slut, I would no be easily persuaded to do this as a public act. It is somehow deeply intimate in a way I can't quite figure out yet.
But...
The whole process was very charged. It was very powerful to have a nice hard erection while being topped and peed on. It made for some wonderful play after (after a good cleanup, of course.
I'd thought about this for a while, was at first very skittish, but as my relationship with someone deepened, so too did the ability to trust her in a way that opened that door.
I suspect this will happen again at some point, perhaps with more elaboration (this being very spontaneous).
