Joe Jonas -- A Little Birthday Fun in Vegas

Joe Jonas had a small celebration for his 25th birthday in Las Vegas ... with two tiny strippers and David Copperfield. We'll explain ...

Joe hit up a Copperfield show at the MGM Grand where he got pulled up on stage and David asked him when he last got laid. Joe said it's been about a month ... the crowd loved it.

The main event went down Saturday at Beacher's Madhouse ... where Joe was once again called up on stage. But instead of a magician, he was entertained by two little people strippers ... a mini Miley Cyrus and a girl who holds the distinction of being one of the smallest strippers in the world.

We're told the Beau Joie Champagne was flowing ... along with several bottles of Casamigos Tequila sent over by George Clooney.