While one's (such as, a street seller or a
stranger)
back is turned to you, you walk away quickly, so when one's
back is turned back around to return to you, they'll see that you're not there anymore.
A product seller at the Flamingo Hotel and
Casino had given me a
free iPhone 7/8 Screen Protector, he then was trying to sell me an
iPhone Screen Protector for my iPhone X phone. He had turned his back to me to walk over to retrieve the appropriate screen protector, which gave me the opportunity to ghost him.