Video example

Incredibly easy to perform guitar trick

Performance:

Play pull off to any open lower string (I used 5th string in the video) and immediately deeply dive the whammy bar.

After that begin to release the lever very slowly for about half of the way,

then fast dive the bar again with a bit less amount of pressue

and release again but this time somewhere higher than in previous release.

Continue this circle of diving and releasing depending on how many gears you'd like to switch :)