I tell them to cool it or leave. My kids don't need to be exposed to such stuff.

This is a difficult conflict because the couple are likely to be your close friends or relatives if they are staying at your home for the holidays. You have three solutions, turn up the radio outside the room to kids music. This will both dampen the mood and cover up the adult sounds that you don't want your kids to hear. The second option is to create sound dampeners or DIY baffle quilts to sound proof a side of your kids bedroom to absorb sound that may come through from the next room. You can also buy soundproofing panels for your home. Lastly, you can move your kids to a sleeping area out or hearing distance from the noisy couple. For example, you might even throw a family sleeper tatami style in your master bedroom. Throw a tent indoors and camp out in the living room. An extreme but awesome idea would be to do a campout in your yard with your kids. Add s'mores, warm blankets and storytelling. The holidays don't have to a horror.