Monroe sang what is now an infamously sex kitten-esque version of "Happy Birthday, Mr. President" immediately after Callas sang "L'amour est un oiseau rebelle" from Bizet's Carmen for a crowd of more than 15,000 audience members.
Callas had flown to New York from Paris while she was between a concert engagement in Germany and the beginning of rehearsals for Medea at La Scala. After singing at the concert, she attended an after-party at Arthur and Mathilde Krim's apartment with Costa Gratsos. She stayed for roughly an hour and a half, but didn't depart before getting some nice pictures with the Hollywood icon.
Monroe was the talk of the evening with her cotton candy blonde bouffant by her hair stylist Kenneth and wearing a Jean Louis nude-colored soufflé chiffon gown embroidered with 2,500 rhinestones (rumored so tight she had to be sewn into the dress...with no undergarments). The original cost of the dress in 1962 was $12,000. In 1999, the dress fetched over $1.26 million at a New York auction.
[Source, Source, Source]
