While working as a radiology technician in a hospital emergency room, I took X rays of a trauma patient.  I brought the films to our radiologist, who studied the multiple fractures of the femurs and pelvis.

"What happened to this patient?" he asked in astonishment.

"He fell out of a tree," I reported.

The radiologist wanted to know what the patient was doing up a tree.

"I'm not sure, but his paperwork states he works for Bob's Expert Tree Service."

Gazing intently at the X rays, the radiologist blinked and said, "Cross out 'expert.'"