In general, an exclamation of displeasement. Started on Mork and Mindy show, continued through Tribes and its various children (Tribes Aerial Assault, Tribes 2)
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!