From the World Naked Bike Ride in New Orleans June 2015
Question for everyone.
Do you think this woman was in the process of jumping up and down or swinging her tits around when this picture was taken?
Keep in mind that she is leaning back a bit.I can see where she was swinging her tits around but who knows?
I would suggest two possibilities:
1) She has mastered the notably difficult sequence of reciprocal excitation body thrusts to cause her tits to continue to both swing circularly in a dual-pinwheel spin. That's my kind of harmonic motion, for sure!! (Maybe on strong enough amphetamines, she could helicopter right off the ground...)

2) She is sitting topless, hanging on well I hope, on the back seat of a performance racing motorcycle - that has just Accelerated Hard from a standing start. The photographer had a lucky snap of a highspeed sport exposure. Inertia has caused her to begin leaning back, as both her tits begin to slide upwards along both sides of her torso.
The best part, that the photog would have been even luckier to catch, would have been the moment a few split-seconds later, as both boobs reach the peak of their arc - and simultaneously smack her in the face, both cheeks. (!!!!!)

Ouch.
-D'Artagnian
Would have been a good one for "MAD's Scenes We'd Like To See"...