Okay, so it's kind of a kinky thing. Kind of.

If you've ever heard of an omegaverse AU, you're probably in a fandom. It's an alternate society/universe where people are assigned a 'nature' once they reach around puberty, and they become an Alpha, Beta, or Omega. Society is kind of like the relations in a wolf pack- Alphas are on top, Omegas on bottom (Betas are pretty much normal people in the middle, nothing special about them). Omegas have heats (like a cat or rabbit, or pretty much a whole crapton of animals) and they curl up in a 'nest' (whether it be a bedroom, closet, etc) and wait for their Alpha (their mate) to 'help them'.

I haven't been able to find any sort of mod that would allow me to replicate this sort of thing. Heats could be considered kind of like a period, happening in certain time intervals (most people say it's either once a month or three/four times a year), and usually trackable. I'm thinking for a Sims version, when a sim would go into heat, the wants would change to 'Have woohoo with...." and things like that. Does anyone know where I can find a mod like this?

ACR is probably the closest thing.

http://www.simbology.com/smf/index.php?topic=19.0