Madonna was reunited with ex-husband Sean Penn at the screening of her new short film.
The Hollywood actor and director, 53, was among the audience who saw the Queen of Pop don a black leather mac to share the stage with her balaclava-wearing 13-year-old son Rocco as they unveiled the film.
The Daily Mirror reported that Madge, 55, crouched on the floor and sang as Rocco, the son of director Guy Ritchie, showed off his dance moves.
When he took off his mask at the end of the routine, his pop star mum pretended to faint and was taken away by actors dressed as cops.
Sean posed with his arm around Madonna, who he was married to for four stormy years until 1989, at the event at the Gagosian Gallery in New York.
Madge described the 17-minute black and white film, SecretProjectRevolution, which features the singer as a prisoner and a bondage-style prison guard, as "aside from my children...the most important thing I've ever done".
Other guests at the party included Lindsay Lohan, Calvin Klein and David Blaine.