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1.
to be extremely upset, angry, and/or agitated.
(Common American Idiom)
He bought a ticket for that specific flight, so therefore he was really fit to be tied after the airline agent refused to issue him a boarding pass.
by Gary Dunn May 29, 2006
 
2.
very angry, furious
My teacher was fit to be tied when my classmate said She didn't know the answer.
by The Return of Light Joker September 16, 2008