Touching one of those caps was a hell of an experience. It was similar in many ways to a squirrel tap with a wrench in the auto shop (for those who didn't do auto shop, a squirrel tap with a wrench is when somebody flicks your nut sack from behind with a wrench. Properly executed it would leave you doubled over out of breath).
He said his coworkers would sometimes toss a television capacitor at each other as a prank.
Those capacitors retained enough charge to give the person unlucky enough to catch one a considerable jolt.