Refers to someone who is being particularly surly, moody, sour or otherwise unpleasant, a.k.a., a bitch... someone you might approach in the same way as a bag of fighting cats.

Best when said in a real Irish accent.
She's like a bag o' cats.
by onthefringe July 30, 2008
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An extremely bad hangover which results in your stomach feeling like a bag full of cats
Oh shit man, I feel like a bag of cats

Wow! last night was loose, I feel like a bag of cats right now
by A-Bomb1508 June 18, 2010
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Refers to someone who is being particularly surly, moody, sour or otherwise unpleasant, a.k.a., a bitch.

Best when said in a real Irish accent.
She's like a bag o' cats.
by j-baby's baby July 29, 2008
Get the bag o' cats mug.