I’d never heard of this prank before visiting this website, The Invisible Rope:

The Invisible Rope is an age old prank that gives the illusion that there is a rope being held, when in reality there is nothing there. It requires two people (one at each side of the street) acting as if they are pulling a rope. The prank is meant to be used on cars; however, we at TheInvisibleRope.com have used the rope in other aspects of life, for your entertainment

Their christmas video is pretty funny, especially when they go in the mall. I love when those two guys do a running jump to hop over the “string”.