Lady Gaga made a surprise appearance at her best friend's show at a New York City bar. Mother Monster took the stage at the Brian Newman Quartet show at Rockefeller Center's SixtyFive bar to play some of her favorite jazz standards, such as "Orange Colored Sky" and "Bang Bang (My Baby Shot Me Down)."

"It was already pretty crowded when I got to the bar," Max, a Gaga Daily reader, who was lucky enough to be in the audience, told us. "At one point, a girl sitting right in front of me turned around to make eye contact with me, and that's when I realized I was literally two feet from Gaga. She kinda gave me a 'don't give me away' stare, so I didn't say anything but freaked out internally. Halfway into the night, Brian introduced a special guest to join him on the rest of his performances for the night: Gaga, obviously. It was surreal to watch her perform so close. Her voice, of course, was phenomenal. Altogether, she was just having a really good time singing with her friends while hanging with her family and the Haus. It made me really happy to see her so happy and to know that she's surrounded by so much love in her life."

Enjoy the video, courtesy of Max and Maxim, below...