The King of Queens - Season 3 Episode 9 -

When Kelly's great aunt dies, both Deacon and she have to go to Chicago and they have no one to watch their two kids, so Doug and Carrie offer to watch them while they're gone. When they first start watching the kids Carrie was terrified of the idea, but soon after they began to love the idea, up until Kirby catches Doug and Carrie being intimate in their parents' bed.