A sudden involuntary jolt that occurs as one is about to fall asleep. Relates to the nervous system. The term most closely relates to falling asleep in a classroom or public setting. However, a shambo can occur anywhere and can be of varying intensity. A minor shambo is surprising yet most often goes unnoticed by bystanders. More severe shamboes can result in anywhere from minor to major bodily injury of the afflicted or those around them.
"In third hour I had a huge shambo that shook my whole desk."
"Last hour I shamboed so bad I almost defacated in my pants."
"Last night I was about to go to sleep, but then I had a major shambo. I couldn't get back to sleep after that."