5x01 "The One After Ross Says Rachel"

After having said the wrong name at the altar, Ross tries to patch up things with Emily. Monica and Chandler try to find some alone time in London but can't seem to get any. Upon returning to New York, the couple attempt to put their brief fling behind them only to find that some feelings can't be ignored. A prank to Monica's and Chandler's utter dismay, the film My Giant has kept them from having sex, in London as well as on the plane to the USA.