The One With All The Rugby - S4-E15
Visible crew/equipment: When Phoebe walks into the apartment while Ross and Joey are watching rugby on TV, the boom mic and a bit of the overhead studio lighting can be seen right before she sits down, and the boom mic can be seen again when Joey stands up after Chandler walks in with Janice.
Answer: The statements that she's contradicting (that it is common, it happens to every guy, and it's not a big deal), are the things that a woman commonly says to a man who is suffering from erectile difficulty, typically to assuage his bruised ego. However, most men do not believe that these statements are true, as evidenced by Chandler's outburst. He's so caught up in the proof that women are lying about it that he gives himself away.
Rooster of Doom