Short answers, pulled from the story.
Sexy Sadie is a song John Lennon wrote in India in 1968 in response to reports that Maharishi Mahesh Yogi had made a sexual advance on actress Mia Farrow. Lennon originally titled it "Maharishi" but changed the name at George Harrison's request before the song appeared on The Beatles double album.
George Harrison insisted the title be changed if the song was to be included on the album. According to Harrison's account in the director's cut of the Beatles Anthology documentary from 1995, he persuaded Lennon to rename it "Sexy Sadie" rather than directly naming the Maharishi.
Yes. During the MeToo movement, Farrow confirmed she was sexually harassed by the Maharishi, describing the moment as: "Suddenly I became aware of two surprisingly male, hairy arms going around me." George Harrison and Paul McCartney had previously said they believed the original story was fabricated by Alexis Mardas.
According to Mark Lewisohn's The Complete Beatles Recording Sessions, published in 1988, an early outtake captures Lennon demonstrating the song with the lines "Maharishi, you little twat / Who the fuck do you think you are?" These were replaced before the recording was finalised.
The piano riff in Radiohead's "Karma Police" closely resembles the piano part in "Sexy Sadie." Ringo Starr referenced the song in "Devil Woman" from his 1973 album Ringo and in "Drumming Is My Madness" from his 1981 album Stop and Smell the Roses. George Harrison also referenced it in "Simply Shady" on his 1974 album Dark Horse.
At the 50th anniversary of The Beatles album in 2018, Jacob Stolworthy of The Independent ranked "Sexy Sadie" sixth out of the album's 30 tracks. That same year, Time Out London placed it 14th on its list of the best Beatles songs overall.