look up any word, like the eiffel tower:
 
1.
1. F.i.fu. (acronym) for Fatigue Induced Fuck-Up.

or
2. Fi.f.u. (acronym) for Fatigue Induced Foul-Up.

(censored version).

3. When one is so tired the easiest tasks are easily errored.

(Sometimes while the person doing the F.i.f.u is unaware

of it until after the fact).
1. (can be used as a verb.) I was so tired I Fi.fu.'ed, and

got off the bus at the wrong stop.

2. I was so tired I F.i.f.u'ed and, tripped going down the

stairs.

3. There was a complete F.i.f.u. on your T.P.S. report

Jonson, you obviously need some sleep.

4. Well todays' paper-work has been a total Fi.f.u.
by Philly McWilly February 29, 2012