The film, released in 1997, tells the story of unrecognised genius Will Hunting whose life changes after meeting Dr Sean Maguire, his therapist.
Williams won an Oscar for the role of Maguire the following year, and received a standing ovation for his victory.
One particularly acclaimed scene shows a conversation between Hunting and Maguire in which they discuss the latter’s wife, who died years before.
At one stage, Williams goes off script – and Damon fails to hold it together.
“She used to fart in her sleep,” Williams – as Maguire – improvises. “One night it was so loud it woke the dog up.
“She woke up and was like, ‘Oh, was that you?’ I’d go, ‘Yeah’ – I just didn’t have the heart to tell her,” he continues.
Damon as Hunting – crying with laughter – asks: “That she woke herself up?”
When Williams nods, the pair erupt into even more laughter.
The moment, which has resurfaced years after being shared on Reddit, seems to have been so hilarious that the camera wobbles as the operator laughs along with the actors.
At the beginning of the clip, you see Damon look to the side – presumably at director Gus Van Sant – to see if he should go along with Williams’s improvisation.
In contrast to this, a scene from Williams’ 1993 comedy Mrs Doubtfire was deleted from the final film for being too heartbreaking for families.
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