Source Engine - What is a "hairball"?

I was playing around in GMod one day, and I noticed a strange command:
CreateHairball
Curious, I tried it out. Strangely, it created several rope-like NPCs that flew away randomly. Killing them crashed the game.
Not only was it in GMod, but Half-Life 2 and Portal had them as well. But what exactly are they, and why are they there?

garrys-mod source-engine

Pictures about "Source Engine - What is a "hairball"?"

Source Engine - What is a "hairball"? - Black Jets Flying Through the Sky

Source Engine - What is a "hairball"? - Blue and Yellow Jet Plane on the Field

Source Engine - What is a "hairball"? - Performance of modern military aircraft with colorful smokes flying in cloudy sky

Is the source engine a good engine?

Is Source a good engine? Facial animation, physics simulation, and smooth performance seem to be secondary (or non-existent) considerations in most engines, but they're incredibly vital for immersion. Source is important at the least and still groundbreaking at best for making these a focus.

What code does the Source engine use?

Source (game engine)Developer(s)ValveWritten inC++MiddlewareHavokPredecessorGoldSrcSuccessorSource 23 more rows

Can anyone use the Source engine?

If your game is not going to be commercial, you can use the Source engine for free, but then you will have limited access to the engine and be at the mercy of the SDK tools.

What does Source SDK stand for?

A software development kit (SDK) is a set of tools provided by the manufacturer of (usually) a hardware platform, operating system (OS), or programming language. Check out this open source SDK.

Hairball - Where is Hairball - Nine Afterlives Achievement - World of Warcraft Shadowlands

Sources: Stack Exchange - This article follows the attribution requirements of Stack Exchange and is licensed under CC BY-SA 3.0.

Images: Martin Dickson, Pixabay, Dalton Douglas, Harrison Haines