Jiggling

[Tina]

The art of a womans tits or ass jiggling when she walks, runs, jumps or does any other physical excercise. Jiggling may also occur in a lowered car or lifted truck with stiff springs.

[Becky]

Bouncing boobs up and down

[Dave Paprocki]

To laugh so hard, and with your diaphragm that your entire body or upper torso jiggles/moves violently up and down.
JOL:Jiggling out loud
Jig is a shortened version
Jiggle:verb form, or a joke funny enough to cause jiggling