You've probably heard of the four clans: ThunderClan, WindClan, RiverClan, and ShadowClan, who abide by a lake somewhat near the Sun-Drown place. But far into the future, a new clan emeged from these, making the number five: MatingClan.
These cats were the especially lusty ones: the females who couldn't be satisfied by masturbation while in heat, and the males who couldn't control themselves after noticing this. They resented having to control themselves and have sex with only their mate, in private. Why shouldn't we be able to have sex with whomever we want, whenever we want? They reasoned. And so they seperated from their respective clans to form a new one.
In time, MatingClan grew to be the most powerful clan in the forest, considering how many kits they produced and how in shape they were from all that sex. As a result of their great numbers and sex drive, they created some new rules.
First of all, frequent raids were conducted on the other clans, to increase territory size for the ever-growing clan, and to capture cats. Any cats captured became slaves, and their kits in turn became slaves for MatingClan as well. Slaves purposes were mainly to hunt. If they caught at least three pieces of prey, they were mostly left alone. (Three pieces being enough to feed the ratio of warriors. They'd have to catch more than that to feed themselves.) If they did not manage this, or ate before the warriors, they were raped. However, some slaves were lucky enough to become Caretakers, a sort of queen/medicine cat combination, to raise all the kits that the warriors could care less about, and heal warriors injured from raids or over-eager partners.
Next, there were the MatingClan cats themselves. At their apprentice ceremonies, their virginities were taken by the current leader. They were taught by their mentors to fight, but mainly to have sex. Their final assessment was to make at least one warrior orgasm just from watching them have sex with their mentors. Warriors did not have any duties other than to conduct raids or train apprentices. When a new deputy was needed, the leader "assessed" the warriors to see which had the best sexual abilities. A leader was not given nine lives, as MatingClan's ancestors, LemonClan, did not have that power, but they were granted the power to see which cats could give them the best sex, a great gift.
Other than that, MatingClan was the same as the other clans.
If you don't like it, don't read it. Simple as that.