The rhythmic movements of a woman's body will be mimiced by the movement of her chest in a way that is almost as hypnotic as a lavalamp. Women that have undergone implant surgery to make their breasts unnecessarily large (boob job) will usually lose The Wabum Effect
Without naming it specifically, Robin Williams helped to define the Wabum Effect by saying "Fake tits are like nazis; they don't laugh, they don't dance, it's just HU-YEAH! I'M WALKING HERE!"
Man 2: Nah, not my style. They're totally fake, I like a girls tits to wabum, it's just sexier when they move like that!
Man 1: I don't care if they wabum or not!
Man 2: Then go for it!