This is in the episod where Joey and Chandler invent the game fireball, and Ross tries to help Joey write a play. Joey and Chandler are talking about their security deposit, and Joey says "I think we said good-bye to that when we invented (something, i can't quite remember) darts. Chandler says "Do you even remember which part of the wall is not spackled?" and Joey says " yeah, right here, and punches a hole in the wall". A few minutes later, they show the wall again, and the whole is not there anymore.