The Zen Slap:

"If you read through enough Zen koans, you’re quickly struck, as it were, by the number of those oblique lessons that end with a student getting slapped. It may be delivered by hand, stick, sandal or goat bite, but the slap, painful as it might be, is an act of compassion, a wordless reminder of the things we know but can never seem to remember or practice for very long."

-- http://www.siliconbeat.com/2008/10/09/of-course-if-theres-no...