In general, an exclamation of displeasement. Started on Mork and Mindy show, continued through Tribes and its various children (Tribes Aerial Assault, Tribes 2)
Robin Williams is credited with inventing the word "shazbot".
From Mork & Mindy, but it has reappeared throughout pop culture over the years. For example, it has been used by the aliens in the Simpsons (dating to at least 1995, before "Tribes" - see www.snpp.com/episodes/3F04.html).
Example 2: Spending 15 minutes trying to sneak into the enemy base only to step on a landmine in front of their generator... SHAZBOT!
***This is the CORRECT spelling of the word. Proper credit must be given to the true comic genius of Robin McLaurin Williams (July 21, 1951 – August 11, 2014) R.I.P.