10 Friends Moments That Were Totally Unscripted
8. Rachel Has "The World's Worst Hangover"
In the season six premiere "The One After Vegas," Ross and Rachel wake up to discover that they got drunkenly married the night before, and she spends the episode convincing Ross that they need to get an annulment.
When Ross doesn't take her concerns seriously and suggests they just stay married, Rachel fires back with the all-timer quip, "This is not a marriage, it's the world's worst hangover."
The script for the episode actually had Rachel say the decidedly less-funny line, "Stop saying the word marriage!," but when Aniston and the crew felt it wasn't good enough, she improvised the hangover line instead.
Better still, the line was so rapturously received by the studio audience that long-time series editor Stephen Prime had to cut the laughter and applause down, and also use an alternate take for Ross' reaction which wasn't muddied by the audience's response.