NEGATE: (Whatever causes the screen to shake)
---Frame: center horizontal position on X("character")
---Frame: center vertical position on Y("character")
(Whatever causes the screen to shake)
---Frame: center horizontal position on (X("character") + random(32))
---Frame: center vertical position on (Y("character") + random(32))
You'd have to play around with it to make it work the way you like.
What, your entire display? I'm pretty sure that wouldn't be possible without messing with things you probably shouldn't mess with. Though, if your game is fullscreen anyway, it would do the same thing.