Friends Season 6 Episode 15 The One That Could Have Been, Part 1
The friends continue imaginning the alternate reality: now, Chandler and Monica sleep together, Rachel almost has an affair with Joey, Ross has a threesome with Carol and Susan and discovers Susan's a lesbian, Phoebe has a heart attack and is fired from her job.
One of season six's best. This episode was amazing, I just couldnt believe the writers could come up with such a great idea. The first time I saw it and saw the plot on Wiki I thought it would suck, but after seeing it I have to say: wow! This ep is great!