From the military, it's an acronym for
Taken
Out
Back
And
Shot in the
Head

Usually it's a term to make reference to a person that gets a group into FUBAR occurrences multiple time.
"Ollie! You should be TOBASH! You've gotten this all FUBAR, your a freakin' clusterfuck magnet. We're gonna deep six yo ass bytch!
by Leif April 12, 2005
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