Hertz donut

noun1

1. •
   (US, humorous) A supposed snack offered to a person as a prank; if they accept, they are punched or otherwise hurt in some way.

   • “[…] Hey Abigail, do you want a ‘Hertz Donut’?” / “Okay.” / I gave her a playfully hard punch on the arm. “Hurts, don’t it?” — 2003