This requires one friend and you must know how to do the roadie run glitch, it can be done on ANY map!
First, do the roadie run glitch (up, right or left - whichever way gap is, and down while sliding to cover).
Next, you need to find a high place like a drop or steps.
After that, find a wall near the steps that you can have your back to and still be able to dive into the steps.
This is where the friend comes in play, have the friend stand in front of you so when you hit down (left stick) + A you don't go back to cover.
You will start twitching, once you get down twitching you will notice one thing - your Controls are messed up!
Left is now down, (we press down+A) so dive towards the steps or drop.
Instead of falling, you are now walking in mid air! You can press B to stand on any object that is in your way.