This is a slip up from the start of the episode where rachel is trying to ask out josh through a note she was going to place in his coat after he had purchased it.....

the gang are sat down in the coffee house and rachel very clearly screws up a paper in anger, throws it aside, and starts again...chandler then reaches over for the notepad in rachels hand and reads "call me back someday guys like you never go out of style....." he then says "what did you throw away?" now how could he have read that when rachel threw away her last attempt at a note and was about to start from scratch on the new notepad page.