This is patched. You can still do it on Black Ops 1, but it recently got patched on Black Ops 2.
It is patched because Treyarch is against dropshotting, that's why when you drop shot, you get killed by skill-less players.
You can't snake anymore in Black Ops 2, you character does this weird t-bagging action. You don't go prone anymore because Treyarch patched the prone speed in Black Ops 2, therefore making dropshotting useless.
In Black Ops 1, you prone fast enough to do this action, but in Black Ops 2, you prone slower in that game, eliminating this snaking glitch.