A law of physics generally attributed to Anime, in which breasts move independent of gravity and jiggle absurdly with even the smallest motion.
"Dude, did you see that chick?" "Yeah, she was Gainaxing so bad, I thought she'd get a black eye."
"I would run more often, but not even my sports bra can stop the gainaxing. it really hurts my back."
animating each and every single frame of breast movement with love and passion.
joe: did you see the last part of the movie of tengen toppa?
random guy: yes, they use the gainaxing in the yoko breast very well