Quote from Monica in The One with Rachel's Going Away Party
Chandler: Hey, Mon, I think I've figured out whose handcuffs they are. Monica: You did? How? Chandler: Well, I was cleaning out the closet and I found some pictures of them ... being used. Monica: Oh, my God. Let me see. Joey: Who's that dirty old lady? Chandler: Monica's grandmother. Monica: Nana liked it rough!