If this is an internal/mental fantasy, i.e. it's just something that get's you off, and right afterward you have no interest in it, then maybe it's your own sexual exploration going on is all...

If you actually did this once, it's still sexual exploration.

If you drank your pee as a kid it was exploration.

It's prolly not gay unless you start making a habit of it and stop dating chicks.

two pennies