I think the song you are referring to is "How Low Can You Go' in which Ludacris does half of the bridge in a distorted litlle kid voice.
Ludacris- How low can u go
Christopher Brian Bridges is ludacris name
Organized Noize
Chris Bridges
Money Maker - Ludacris ft. Pharrell
Ludacris
the song is "baby" by justin bieber featuring Ludacris
Ludicrous aka Luda feats Justin Bieber in baby
Kyra Alley
Ludacris
Ludacris.
Ludacris
Ludacris
Justin Bieber- Baby ft Ludacris
Ludacris.
Ludacris helped Justin Bieber with his song Baby.
Ludacris - Get Back oorrr Flo Rida - Get Low