I was recently reminded that I originally planned a consideration of GAINAXing as a shorter companion piece or addendum to my remarks on the pantyshot. Perhaps these things are better for being mulled over for a month or so.
GAINAXing is, like the pantyshot, a form of revelation-without-revelation: it draws the viewer’s attention to the fact that There Are Breasts without the animators having to draw any breasts per se (although in Gunbuster‘s case, the animators were quite happy to draw breasts per se as well). Given that this is anime and so everything has to be drawn by a human, GAINAXing is also like the pantyshot in highlighting that what you’re watching isn’t real: the animators are responsible for the exaggerated effects of gravity just as they’re responsible for all those fortuitous gusts of wind which send skirts reaching for the sky. And the more detailed the GAINAXing is (for example, if each breast possesses its own independent movement), the more attention – slightly worrying attention – has been lavished on their work by the animators.
The mention of movement leads me to the element that distinguishes GAINAXing most sharply from the pantyshot: breasts can only bounce in a moving medium. In a static image, the best the artist can do is perhaps some movement lines and an onomatopoeic sound effect. It’s a kind of fanservice which is uniquely suited to animation. Or, to put it another way, .jpgs no, .gifs yes.
Much more recently – only a few months after the twentieth anniversary of Gunbuster‘s first episode – we’ve been blessed (?) with a GAINAXing effect caused by switching from zero-g to artificial gravity in the premiere of Macross F. Although I haven’t seen everything produced in between the two, so I can’t say for sure that this is Satelight’s own invention or an idea they borrowed from elsewhere. To me, this still image drives home the need for movement: if it’s frozen in time, an instance of GAINAXing can produce downright wierd proportions and aesthetically displeasing shapes.
(See, I made it through the whole entry without sounding a note of moral disapproval. Look Mum, no qualms!)
Animanachronism 
I kind of wonder whether this could be done in live action film in the way that pantyshots can (perhaps through some kind of concealed device). Motion is surely necessary, but I reckon animation is ideal for the fantastical/exaggerated not seeming too incongruous. Or is that just because it’s a trope we’re used to seeing? It’s not like mainstream actors always look like regular people anyway. Was the (hypothetical) first GAINAXing shocking, was it a virtuoso innovation in the field of pointing out breasts to the innocent viewer?
Also, I reckon GAINAXing differs from the pantyshot in presenting the movement as part of the universe physics. Not that it isn’t massively contrived – but it isn’t targeted at a specific character. A pantyshot is often contrived by plot, while this occurs to all breasts (of a given magnitude) within the show. It’s the difference between the plot making an artificial spectacle out of a social fetish and the “universe” making one out of a physical characteristic.
I was kinda expecting a Gainax Ending dissertation but an entire post dedicated to the fanboy favourite that is the Gainax Bounce was a pleasant surprise…I salute you sir. ^_^
Funnily enough, I too noticed that moment in MF in which Cheryl is exposed to the gravity field and immediately thought “Anno would approve.” This particular aspect of sci-fi anime is still alive and well.
Another, less pressing reason to use the Bounce would be some kind of boasting regarding the animation. There’s a certain feeling of “life” (uh, yeah) to this – obviously, as motion is the best way to portray life through a visual medium.
So, ironically, while it makes obvious that it’s animation – it’s also a life-giver to the world. Realistic-ish dis-suspense of disbelief?
I kind of, sort of agree with Kaiserpingvin. Though it’s ridiculous, it does add life to the animation.
Is it not surprising that Gainax’s defining work, Evangelion, does not feature the Gainax-bounce at all (or does it …)?
@ coburn: I suppose it could be done in live-action (through CGI if nothing else) but I think your suggestion that it seems easier to accept in animated form is spot on. You’re right, too, that it doesn’t have the targeted feel of the pantyshot which frequently has a feel of ‘and the writers decided that you would be humiliated here’. But there are shows where it’s not exactly a fully-integrated element of the universe’s physics: in Gundam SEED the captain of the Cool Ship GAINAXes in a piece of stock footage which is deployed whenever said Cool Ship is hit, but her second-in-command doesn’t. Until, that is, the second-in-command (Natarle, if I recall correctly) gets promoted and given a ship of her own, at which point she begins to GAINAX too . . .
@ concretebadger: Ah, it’s the fanservice-analysis which prevents this blog from descending into true academic dullness.
@ kiaserpingvin: Good point. It might be fairly unrealistic (though of course GAINAXing does occur in real life, but not as dramatically or frequently) but it does give us an animated world which is more than two static figures with their mouths flapping at each other.
@ CitizenGeek: It’s a while since I saw Eva last, so I couldn’t say for sure. Maybe when Asuka tries to teach Shinji about thermal expansion in episode 10?