Go is used before a number of adjectives to talk about changes. This is common in an informal style.
Go, for example, is used to talk about changes of color. This usage is common in British English.
Examples are: go brown, go green, go white, go black, go blue etc.

Go blue with cold
Go red with embarrassment
Go green with envy

Leaves go brown in autumn. (NOT Leaves get brown in autumn.)

In American English, turn can be used instead of go.

Leaves turn brown in autumn. (US)
She went red with anger. (GB)
She turned red with anger. (US)

Go is also used in a number of common expressions that refer to changes for the worse.
Examples are: go mad; go crazy; go deaf; go blind; go grey; go bald etc

Horses / bulls can go lame
Iron can go rusty
People can go mad / crazy
Vegetables / fruits can go bad

Milk can go sour
Car tyres can go flat

He went bald in his twenties.
The milk has gone sour. OR The milk has gone off.
The lemonade has gone flat.

Before the adjectives old, tired and ill, we use get.

When I get older, I get happier. (NOT When I go older, I get happier.)