hair ball, hairball n. A compact mass of hair that forms in the stomach of animals as a result of licking fur; as, the cat coughed up a hairball right on the new rug.
... A large batch of messages that a store-and-forward network is failing to forward when it should. Often used in the phrase "Fido coughed up a hairball today", meaning that the stuck messages have just come unstuck, producing a flood of mail where there had ... — The Jargon File, Version 4.0.0
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