Jazz Club Concertgoers Were Chillin' When Lady Gaga Suddenly Walked In and Sang Frank Sinatra

Lady Gaga walks into a bar . . .

No, seriously, she walked into Hollywood bar and lounge Black Rabbit Rose on March 14 and surprised customers with an amazing performance of Frank Sinatra. Donning a dark halter dress with a fur jacket, the 32-year-old Oscar and Grammy winner popped into the venue and chatted with the crowd before singing a couple of Ol' Blue Eyes classics.

"I'm here to ruin the party. So sorry," she joked in a video captured by audience member Andrew Kimmel. "My whole life, you know, I've been called irresponsible. It doesn't make me so mad because it's kind of true. I like to hear the truth." She then started belting Frank's 1963 hit "Call Me Irresponsible" — and if you're at all familiar with her vocal chops, you'll know she has a knack for strong jazz sets. Gaga also took listeners on an out-of-this-world trip with her rendition of Frank's 1964 cover of "Fly Me to the Moon."

The past year has been rather eventful for Lady Gaga, considering her breakout role in A Star Is Born, Vegas residency, magazines features, and successful award season. She also recently announced that her sixth studio album is in the works, sending Little Monsters into a frenzy. And after her recent surprise show, we're hoping the LP will be a fun fusion of pop and jazz. Watch her full performance at Black Rabbit Rose ahead!