You can use this package to decode any QR codes spotted by your Parrot AR.Drone's camera.
brew install cairo ffmpeg
This program outputs all of the decoded QR codes to the console:
var QRAR = ;var drone = ;var codes = drone;codes;codesstart;
This program starts an ar-drone REPL:
var arDrone = ;arDrone;
So if you pipe the output of the first program (decode.js) to the second (repl.js):
node decode.js | node repl.js
Then you can show QR codes like these to your drone and it will obey!
See felixge/node-ar-drone for the available commands. There are lots of free QR code generators online and apps that work from a smartphone (in fact you can just tweak the above image URLs to get started).