This reminds me of the time when I had a younger housemate and she and her boyfriend were, well, let’s just say they were particularly loud. You know. So one night, on their third go-round at about 2am, I put “Mmm Bop!” by Hanson in the CD player, aligned the speakers to their room, turned the volume up to ELEVEN, and went through the song about five times.
No more sex sounds after that, and I could get some sleep. The housemate was humming Mmm Bop for days afterward, though.
If you want to get passive-aggressive instead of, say, calling the cops, wait until they’re trying to sleep and play some Hanson. It worked for me. :)