Don't even get me started about Stewie X Peter Griffin X Brian Griffin as a thruple
Peters size (small) makes it so he can enter Stewie, and brian isn't a large breed dog so he can fit too
And before someone gets upset because Stewie is a baby, Stewie is a grown ass gay man in a babies body, that's the point of the character, sorry not sorry
Chris often hears the moans of Peter, Brian, and Stewie, while Chris is fucking Lois, it always makes him smile and feel good vibes to know they're enjoying themselves