MECHANIC WAS CHECKING SQUEALING NOISE ON JOB FOREMAN TOYOTA PICKUP. HE WAS SPINNING THE FRONT RIGHT WHEEL WITH HIS LEFT HAND. WITH HIS THUMB ON THE RIM HIS GLOVE CAUGHT SOMETHING ON THE BACK AND PULLED HIS THUMB INTO ONE OF THE HOLES ON THE RIM. HIS THUMB STOPPED ON THE BRAKE CALIPER AND THE WHEEL KEPT TURNING. HIS THUMB WAS MASHED AS A RESULT.