whibble

to whibble is to use (ideally) 2 fingers and vigorously move them in a horizontal action to create a pleasing wobbling action. Breasts and bum cheeks are the usual ideal targets, however, it is only limited to your own imagination.

to put ones finger into a ladies cleavage and move them vigourously - thus whibbling her breasts and jiggling them

When somebody rubs their fingers between a womins cleavage making it bounce about while slappin' that ass.