Back when I was dating my now wife, her and her son were invited for a sleep over at my house for the weekend. I had a spare bedroom for the kid and her and I slept in the same bed. We got up early for a little fun and my wife being very vocal in the bedroom was moaning and at the grand finally she let go a big "Aaahhh" where her son screamed "Mom, are you alright" and she just said "It's Ok, mom just had a bad dream" And he said "I had a bad dream too".
Second story. My son, yes the same boy that had a sleepover at my house, now has kids of his own. My granddaughter's bedroom is right beside her parents bedroom and one night while we were babysitting she went to bed and started to shake the headboard on her bed, hard enough to get our attention. When we entered the bedroom and asked her what was going on she said that mommy and daddy do that often at night before going to sleep and it helps them fall asleep better so she wanted to try it. That was a funny story to tell our son and daughter in law what was going on in their bedroom. Lol. We are pretty open about sex in our family.