Frank Zappa and Yoko Ono
Zappa met Lennon and Yoko Ono in 1971 and performed with them on stage. After a while Ono started screaming throughout Lennon's performance, so two of Zappa's band members put a bag over her head while she kept singing. This track eventually ended up on Playground Psychotics (1992), where it was named A Small Eternity With Yoko Ono.
"Frank once described an encounter he'd had with John Lennon and Yoko Ono. I don't remember the occasion, but for some reason, they were about to go on stage together in New York. According to Frank, Yoko was talking incessantly in a high-pitched voice and John was getting more and more exasperated with her. Finally, John shouted at her: 'Shut up you little Jap!' And Yoko socked him in the face. Ah, those golden days of peace and love. Frank's reaction? 'From then on, John was okay in my book."
Yoko Ono is one of the people receiving thanks for their "very special but no less significant contributions" in The Yellow Shark liner notes.  She and John Lennon were also mentioned and thanked in the liner notes of The MOFO Project/Object (2006) album. 
Yoko Ono about Frank Zappa
"We come from more or less the same background, the classical avant-garde, though in our work we expressed ourselves quite differently. As a composer, I felt a close comradeship to him amongst more rock orientated singer/songwriters. He is one of the geniuses of our time and will always have a place there. He will go on and on and on!" - Yoko Ono, reflecting on Zappa's 70th anniversary on December 21, 2010.
- Richard Emmet, My Time With Frank Zappa