In the first five minutes of the episode where Joey teaches Mr. Treager how to dance, Monica makes Rachel take out the trash. She says to Rachel, "you just put an empty milk carton back into the fridge." Rachel says, "yeah, I know, but the garbage is full." While Monica is taking out the milk carton, she asks Rachel if she's ever taken out the trash, and you can see the carton in one hand and the pizza box in the other. Then, the camera focuses on Rachel and you can see a garbage bag in the same hand that just held the milk carton. (You can see it better once the camera goes back to Monica.)