Badinkadink is a sarcastic sound usually made by a friend when you wimp out on asking a girl out. the sound is suppost to represent a pair of balls (most likely yours) dropping to the ground and bouncing away
Sam: did you ask her?
Troy: No man i was warming up and she left?
Raymond: BaDinkADink! OOOOOOHHHHHH!
Troy: Shut the FUCK Up Raymond!