Quote from Rachel in The One with Ross's Sandwich
Rachel: Oh, my God, that's Monica. Joey: Oh, no. No, no, no, no- Rachel: You get away from me, you sick, sick, sicko! Ross: What's going on? Rachel: Joey has got a secret peephole. Chandler: Oh, no, no, no! Rachel: Yes, he has a naked picture of Monica. He takes naked pictures of us, then he eats chicken and then he looks at them.