I've been finding different ways to expose my wife to my grandparents through the years we've had to stay with them. 

It started simple with sitting with my laptop where they could see the screen. Tell them I have pics of the grandkids to show them but instead have her full naked body pulled up and pretend I made a mistake. 

I've set up a few times for my grandma to walk in on my using my wife's dildo

Id sit next to my grandpa during football and watch full videos of my wife getting fucked by 2 guys and I'd see him watching the whole thing

Then for Christmas one year we bought them a chromecast and I started casting videos of her getting fucked on their bedroom tv.

Their quiet Christian types and don't bring it up but I love they see how slutty she is and she has no idea