The One With Frank Jr. - S3-E5
[After Joey's just drilled through a wall very close to Chandler's head, Chandler runs into the living room.]
Joey: Oh, did I get you?
Chandler: No, you didn't get me! It's an electric drill! You get me, you kill me!
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