go south

verb4

1. •
   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.
2. •
   (slang) To give somebody oral sex.
3. •
   To make an escape; to disappear.

   • He won! A disbeliever, from childhood, in the frequency of miracles, he gathered up seven hundred and forty dollars and "went south" with it. — 1929
4. •
   (slang) To rathole: to take chips off the table in a cash game without exiting the game completely, especially with the intention of limiting losses.