(Cover) - EN Showbiz - Miley Cyrus caused a stir when she performed with a drag queen on Saturday night.

The bride-to-be was enjoying a night out with friends when she serenaded entertainer Vicky Vox at the Roosevelt Hotel Beacher's Madhouse club in Hollywood.

Miley is known for being fun-loving and spontaneous, but her performance on stage was enough to surprise the crowd.

"She was in her usual happy mood and was very social and upbeat," a reveller told People.com. "She was very chatty with everyone at her table."

Singing loudly into the microphone, Miley performed Happy Birthday a cappella.

"It was ridiculous," a source told celebuzz.com. "She normally keeps to herself but she just jumped up, as there were like three birthday people on stage".

Miley dressed down for the occasion, wearing a sleeveless white T-shirt and denim shorts.

The star, who was without her fianc Liam Hemsworth, partied until the club closed. (C) Cover Media