hairball

A usually disgusting ball of hair and other bodily fluids (although, technically, only hair is required to make it a hairball). Cats periodically cough up these vile things.

A hairball that has not yet been expelled is called a trichinobezoar.

hairball n.

1. [Fidonet] 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 previously been drought. 2. An unmanageably huge mass of source code. "JWZ thought the Mozilla effort bogged down because the code was a huge hairball." 3. Any large amount of garbage coming out suddenly. "Sendmail is coughing up a hairball, so expect some slowness accessing the Internet."

--The Jargon File version 4.3.1, ed. ESR, autonoded by rescdsk.