After John Lennon was killed in 1980, there was a massive public mourning in Central Park. All Tuesday and Wednesday there was an immense gathering in the park of people crying, wailing and flailing over Lennon’s death.
That Wednesday night, Rav Soloveitchik gave a weekly parashah shiur in Furst 501. The topic was the deaths of Jacob and Joseph in Egypt.
Rav Soloveitchik set up the Biblical verses to discuss the topic of the mourning laws, in which he emphasized how the Egyptian mourning practices of embalming and the encrypting process was not permitted according to teachings of the halakhah.
He then said: “This [the Egyptian practice] is a case of going to extreme in mourning just like the people are now doing for John Lennon.” In the audience, this elicited an outburst of chuckles, murmuring, and moving chairs closer. When everything quieted down, he continued:
“How do I know from Lennon? You are surprised I know from Lennon. Well, I know Lenin- no one can forget Vladimir Lenin, he was a real troublemaker.[last two words slightly garbled from the murmuring crowd] So I know about Lennon.”
Rav Soloveitchik followed this by using Jackie Onassis [Kennedy] as the model of the opposite extreme of callousness when after Kennedy was shot she shopped for a hat to wear during mourning .
Chabad and Paul McCartney
Since we are speaking about Beatles: The surprise guest at last night’s fundraiser for Rutgers Chabad in New Brunswick was Sir Paul McCartney, who’s apparently dating the daughter of the one of the honorees. h/t JustASC and more details here.
The Book of Doctrines and Opinions: 
I wonder if the Rav knew about Marx (Groucho).