Pinky Promise
When she turned to her right, thinking that someone was calling him, she found nobody standing over there and got confused.
After a few seconds, as Marie looked in front again, the boy who was standing behind, tapped her shoulder again, but this time it was on the left side. Marie turned to her left and, surprised as she was, she found nobody on that side also. The guy was tapping on one side and immediately jumping to the other side to fool Marie, and he was being quite successful in it until Jean caught his hand without looking at him when he was about to tap Marie again.
“What do you think you are doing?” Jean questioned the guy.