You are still here? Well,
If you ever wanted to get this achievement, you had to do this:

1) Open the game
2) Go to Local
3) Choose Sandbox
3.1) Press B to practice with 3 bots (optional)
4) Open the chat and type "Fast Forward"
5) Repeat step 4) several times (5 times to be sure)
6) Shoot the cards to get perks
7) Last: Now shoot in the air (or in the bot)
DONE!

(I hope devs will fix this achievement soon, and this guide won't be a joke anymore)
[Yes, it doesn't work for now.]