A while back, Theifs could be detected by fake square knot ties, the usefulness for this knot is also getting out of it, since the rope easily slips from the other one. So when your freind ties your hands behind your back, this is the knot to use.
Step 4: Over the loop
Step 5: You may now slide the rope
notice that, the rope easily slides, but looks like a square knot, good for magic