Behodar: It's supposed to be one word as it's an acronym: Total Inability To Support Usual Performance.
Nope. It is of military origin and usually means something is dead - it's a bit sexist as it means a female body will float with belly up, while male bodies float with belly down.
FUBAR (farked up beyond all repair) is an acronym. Tits up was not - that acronym came after to jest/justify it. Just look at one always being used all caps and the other not.
FUBAR I knew.