You can talk to them about having orgies, talk about face sitting, or trying new positions in bed.
All you need to do is add the aspiration “Dirty Talker” in CAS and you’ll see new interactions on your pie wheel. Are you tired of your Sims living a vanilla lifestyle? Want to find a way to spice up their sex life with some dirty talking? Thanks to the modder, WICKED PIXXEL, your Sims can flirt and talk dirty to their significant other.