Air Force top brass recently got a shock when they discovered one of their airmen leads a secret life as a rap star.

By day, Senior Airman Bobby Cheek, 26, is a military dental assistant. But, in his spare time, he's Bobby Cheeks, an up-and-coming rapper with a new CD called A Soldier's Story and a video, "Ya'll Want 2 Party," in minor rotation on BET and MTV. Guests on Cheeks' set include veteran mic-controller KRS-One.

The Jersey City native joined the military after high school to escape the streets, but he never gave up his dream of being an emcee.

"A lot of my cousins were locked up and a lot of my friends were shot up, so it was sort of like go this way or that way," Cheek said.

Nobody in the Air Force knew about his rap aspirations until he showed up on the cover of the Air Force Times.

"Everybody from his dental office to the Pentagon was saying 'Whoa, what is this?' " said Donald Gaines, co-owner of Urban Musiq Group, the Jersey-based label that signed Cheek after he joined the Air Force. "We thought because he was doing this on his own personal time, we didn't need to tell the military. But oh, oh, oh--we found out differently."

Officials were nervous that Cheek might have a conflict of interest, but after listening to his recently released CD, and watching his music clip, they just separated themselves from Cheek's musical career--not letting him be interviewed on base, for example, and screening what he tells reporters about the Air Force, sometimes sitting in on interviews.

But they haven't told Cheek to stop rapping and his first Alaska show, which will take place on the base for his fellow airmen, is set for January 8.

Cheek's colleagues were also stunned to see the other side of Cheeks, who they've always known to be "humble."

"It's like a totally different person," said Senior Master Sgt. Young. "I was just like, 'This is Cheek?' "

"He's like Dr. Jekyll and Mr. Hyde," said Gaines who's been heavily promoting the January 8th gig. "He's such a laid back, respectful kid. But when the lights come on and the microphone is in his hand... everyone can see that this quiet young man can act like superman and go in the phone booth and come out and turn the party out."