S1E20 · The One With the Evil Orthodontist

Complete story — includes the ending

Rachel and Barry secretly see each other, even though he is now engaged to Mindy, who asks Rachel to be her maid of honor. When Mindy admits she and Barry had an affair while Rachel was engaged to Barry, Rachel finally confesses to Mindy that she has been sleeping with Barry; the two women confront him, though Mindy decides to marry Barry anyway. Meanwhile, Chandler goes nuts when a woman he likes does not return his phone calls, later realizing there was a mix-up. The friends become annoyed after discovering someone across the street is spying on them. First appearance of the "Rachel" haircut.