"I went, 'Good point"'.
He appeared at drive-in cinema Cineramageddon dressed in distressed jeans and a black hat to speak about the film, but spoke of US President Donald Trump following shouts from the crowd.
Chants of "Oh Jeremy Corbyn" to the tune of Seven Nation Army by the White Stripes were heard as the crowd - said by some Glastonbury regulars to be the biggest they'd ever seen - waited for his appearance.
Mr Corbyn encouraged his audience to look at the wall that surrounds the festival.
Corbyn, a 68-year-old leftist, has not only survived attempts by some members of his own party to oust him but has also now led Labour to unexpected electoral gains against the Conservatives.
First to grace the "loo like no other" was none-other than festival founder Michael Eavis.
But he received loud cheers for comments on equality ("We need to challenge sexism in our society, and homophobia, and any form of discrimination that goes on") and refugees ("Let's support them in their hour of need and not see them as a threat and danger").
The Labour leader was earlier shown being mobbed for selfies by young groupies in the Greenpeace area of the festival site.More news: Huge mastiff named Martha wins world's ugliest dog
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Raucous cheers went up nearly every time Corbyn paused, with the man of the hour having to shout over continuing chants of "Oh, Jeremy Corbyn".
"I'm really proud to have been selected to represent WaterAid at Glastonbury, working as part of loo crew and I'm really looking forward to experiencing the sites of sounds of the festival", Millie said.
"I wore a Corbyn T-shirt a year ago, I think he's a wonderful man and I think it's great that he is getting in touch with young voters".
Holding up a sign with four hearts for each location of the attacks with the words "Love Will Win, Terror Will Lose", one participant explained, "For me personally, there have been some very bad things that have happened in the last couple of months that have probably touched everybody".
He said: "I'd burnt myself out".
But Darren Garrett, from Gillingham in Dorset, took a different view.
Mr Corbyn, who had not attended the festival before, introduced United States hip hop duo Run The Jewels before his Left Field tent speech.