A husband and wife are having sex, and suddenly their young son comes into their bedroom; and upon seeing them, immediately turns around and heads back to his room.
The wife turns to her husband asking, “What should we do?”
“Let me handle this,” he says, getting up to go talk to the boy.
He walks into the son’s bedroom, and is shocked to see him banging away, pounding his grandmother!
The boy looks up at his speechless dad, and without missing a “stroke,” he says, “You 'play' with mine, I play with yours, right?” - The Thing (2011)