The dentist lifted he drill, spun it a few times, then looked down.
The patient was out cold, blissfully unaware of what was about to happen. The dentist brought the drill down and started, digging a hole, digging deeper and deeper, all the way to the hilt of the drill. The patient was still.
The dentist backed the drill out, moved a few centimetres to the left, and drilled again. Again, to the hilt. He backed it out.
The dentist continued this, over and over and over again. Finally, finished, he set the drill down. He looked at his handiwork.
The professor came by to inspect the work.
“Well done, Milo. Maybe don’t go quite so deep next time. You want your patient to have a little bit of gum left. But good, carry on.”
The dentist grinned, retook his arms, and started drilling some more.