I have one fetish and it is very very specific.

One person must be on one side of the edge of the universe, and another person be on the other edge of the universe. Both are naked and ready for the sexing.
And in a split second those two people meet each other in the centre of the universe and one would penetrate the other BUT ONLY ONCE, and in the other part of that second they then go back to the their corner of the universe and that is the end of it.
I call it the big bang.
So far there is no art of this fetish and will likely never be due to image size requirements or the tininess of the characters on screen or both.