I've never heard this expression, so I googled it. I came up with pictures of "short down" jackets, and "short down" skirts. They were all items of clothing that were made from "down", as in "down feathers". These are the soft feathers that make for great insulation. I believe short refers to how long the item of clothing is. Anyway, I've never heard the expression, so I could be wrong. But that is my best guess.

I completely agree with Jerry. For the non-native speakers of English reading this: Please don't use Urban Dictionary if you expect to learn proper English!

I sure hope that you aren't using urban dictionary as a serious resource. It's full of nonsense. It appears that people just make up words and definitions.

If it is 'short brown', it is describing the qualities of something. For example: There was a short, brown chair in the kitchen. She had short, brown hair.

Sorry, It's short brown