On June 1st, 1971, John and Yoko landed at Kennedy Airport in New York, where they were met by Apple's Pete Bennett. They had been issued a two-week visa to enter the country in a continuing effort to track down Anthony and Kyoko Cox and settle the custody issue. With no work permit, John was technically not supposed to perform or record any music during his stay, but that turned out not to be the case.
Within a few days of arriving, John and Yoko had managed to make the acquaintance of several notorious radicals, such as Jerry Rubin and Abbie Hoffman, as well as street musician David Peel, in Greenwich Village. On the afternoon of June 6th, they appeared on WPLJ-FM with their old pal Howard Smith, producing a "happening" in which very little of substance actually happened. Imagine "Revolution 9" being performed live for two hours with audience participation in the form of callers, and you'll get the idea. Here is a 36-minute recording of "highlights" from the event.
Smith went from the radio studio to interviewing Frank Zappa in a hotel room, and brought John and Yoko with him. By the end of the conversation, it was decided that the couple should make a surprise appearance at Zappa and the Mothers' show that night at the Fillmore East. John acquitted himself well on an oldie, "Well (Baby Please Don't Go)", and joined in on Zappa's composition "King Kong", which was hijacked to become "Scumbag":
The performance was later released in differing edits on LPs by both Lennon and Zappa. Three nights later, John and Yoko were back on WPLJ radio, this time for a more conventional interview by Alex Bennett, once again taking calls from listeners (and with John having to step out briefly when overcome by nausea).
On June 12th, John and Yoko attended a party at Allen Klein's home, celebrating his wife Betty's birthday. Also attending were Andy Warhol, Miles Davis, Jack Nicholson, and filmmaker Jonas Mekas, who shot some footage: