To perform the Brettzel stretch, start on the ground. Lay on one side, extending your bottom arm and leg straight out. Bend your top leg at the knee over the other at a 90-degree angle and rest it on the ground as you reach behind yourself with your top arm. Grip your bent knee with the bottom hand, pulling slightly to drive your knee into the ground. Bend your bottom leg and grab your foot with your top hand, pulling your heel toward your butt. Finally, release any tension in your neck and allow your head to relax.

However, when he inserted the words — “You will probably refuse” — before continuing on to ask for a donation, the compliance rate jumped to 39 percent.

That’s why the words, “You will probably refuse,” are so effective: they give people an out. The words make people feel like they are acting out of their own free will and that they’re the ones who are in control of their decision.