Rihanna -- Lap Dance from Tiny Stripper

2/22/2010 1:11 PM PST
Rihanna celebrated her birthday on Saturday night with boyfriend Matt Kemp, a few close friends ... and a little person who gives lap dances.

It all went down in Arizona ... during a weekend in which RiRi went barhopping in Scottsdale.

What more could a girl want?

UPDATE: The tiny dancer is "Bridget the Midget," a porn star who also appeared on "Cathouse."