Go-south meaning

(idiomatic) To become unfavorable; to decrease; to take a turn for the worse.

I should have walked away from the casino when my luck went south, but I stayed and ended up in the hole.

He was unconcerned that his health might turn south.

Yesterday the stock market moved south, ending up on a loss for the day.

Afterward, when company profits had ventured a bit too far southward, the CFO began to get nervous.