In the humorous exchange in the Avengers I, Bruce said:

“I don’t think we should be focusing on Loki,” Bruce said. “That guy’s brain is a bag full of cats. You can smell the crazy on him.”

Thor took a step toward Bruce. “Have a care how you speak,” he warned. “Loki is beyond reason, but he is of Asgard . . . and he is my brother.”

“He killed eighty people in two days,” Natasha pointed out.

Acknowledging this, Thor backed down a little. “He’s adopted.”

I could not locate the exact meaning/implication of "cats" here. So far I have three guesses:

1) There is a phrase "let the cats out of the bag", meaning secrets leaked; so does this mean "Loki's head is full of (dark) secrets?

2) According to Collings dictionary: "a bag of cats" is an Irish informal way of speaking someone "bad-tempered"; so does this mean "Loki is a bad-tempered person? (which I personally don't think it fits the context and the usage of Irish English does not make sense to me in an American movie.)

3) In my culture, cat has some connotation of "smart\clever", which leads to "sly"; so does this sentence mean "Loki's brain is very smart and he is sly?"

Anyone could help me with the "cats" here please? Thanks a lot.


"A bag full of cats" is an Irish expression for a bad-tempered person and that does seem the closest definition to what is intended here. However, that isn't widely known and I'm not sure that is what influenced your quote from Avengers.

Not all metaphors and expressions are out of a book - some are made up on the spot! I think the writer just thought that cats can act crazy, a lot of cats in a bag would act super crazy, so let's say this crazy guy's brain is a bag of cats!

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    Of course, the risk of creating a metaphor on the spot is that it might not work. I really don't know what "brain is a bag of cats" is supposed to mean - or, I wouldn't if he didn't clarify, "you can smell the crazy on him." A bag of cats is crazy? Would a bag of a different kind of animal be less crazy? Is he crazy because he has a bag of cats instead of a brain? Would he be just as crazy if he had a bag of groceries for a brain? – Juhasz Mar 28 '19 at 13:16
  • thanks:), just as you said, the expression meaning a bad-tempered isn't widely known; and more importantly, Loki does not strike me as "bad-tempered", crazy he is, but more like "sly and dark and manipulative", which happens to match my own feeling for cats (no offense to cats, personally the owner of one :). – user86301 Mar 28 '19 at 14:59
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    The sense is that the bag of cats is "crazy" because they'd be fighting and scratching and making loud noises; and a bag of any kind of animal that tends to act this way when it is upset would have the same meaning. "A bag of ferrets" or "a bag of Tasmanian devils" would be similar. "A bag of hedgehogs" does not, since they'd probably all just roll up into balls and be still. – Canadian Yankee Mar 28 '19 at 18:49

In our culture in Moroccan Tamazight variety we say something like "I have cats in my head, brain or mind." It means there are lot of problems or duties that should be fixed or done.

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