What does the word golden sombario mean in baseball?

Answer 1

Nothing, and that's TWO words, anyway.
The PHRASE 'golden sombrero' is bestowed upon a player that strikes out four times in one game. It IS borrowed from the hat trick, but it is NOT three, it's four. Four is bigger than three, so a bigger hat than what gets thrown on the ice was chosen, and hats don't get much bigger than a sombrero.

Answer 2

Depending on whose definition you believe, a golden sombrero refers to a player who strikes out either 3 or 4 times in a game. The term is borrowed from hockey's hat trick.