I have a fantasy of a futa battle royale for "alpha" status.

Basically you have an all-futa society where a certain cohort are grouped together (like a school year, for instance), and they "battle it out", in a sexy battle royale, by trying to render eachother incapable of siring children. Non-lethally, mind you, as the point is that the last one standing with a functional cock becomes "harem queen" and starts knocking up the losers.

Bonus points for "sub"/"fem" futas (who'd rather /be/ penetrated anyway) "surrendering" their cocks to their lovers and hopeful winners, and/or giving up either dick or balls in order to be allowed to keep the other (while those who fight it out and lose have the winner take their whole package).