Justin Bieber's Double-Teamed Stripper REVEALED -- Hot, Blonde, and YOUNG

BEHOOOOLD ... the hot blonde stripper Justin Bieber recently used as a chew toy ... in all her fake-breasted glory ... and contrary to reports, she's definitely NOT old enough to be his mom.

Sources close to the dancer tell TMZ, 26-year-old Karolina began working as a stripper in Vegas very recently after moving from Chicago -- and when Bieber quietly visited Sin City back in January (before his DUI arrest) he handpicked the bunny-tatted dancer to come back to his hotel room.

We were initially told by the owner of the photo that the pic was snapped inside an L.A. recording studio, but turns out it was actually taken inside Bieber's Vegas penthouse.

Sources tell us, Bieber and his entourage hand-picked Karolina and two other dancers to come back to the hotel room for private dances ... and Bieber paid them THOUSANDS each in cash.

As soon as they arrived to the room, we're told the girls' phones were confiscated and they were each required to sign one of Bieber's famous confidentiality agreements, barring them from talking about what transpired that night.

Our sources wouldn't say how far things went between Bieber and the girls -- but we're told Karolina voluntarily posed for the boob photo.