The One With the Breast Milk - S2-E2
Corrected entry: In the scene where Chandler pours Joey a glass of orange juice, even though there are sounds of something being poured, if you observe carefully, you can see that there is nothing in the glass - when the juice is supposedly being poured, and even when Joey is drinking the juice. (00:14:50)
Correction: You can see the juice being poured in the glass. You can see it dribbling. Also when Joey is holding the glass on the counter you can see the liquid slosh around when he moves his hand.