snowball's chance in hell

all hell breaks loose

The situation becomes chaotic or characterized by conflict or rage.

blow one's chance

To ruin, or fail to capitalise on an opportunity.

Buckley's chance

A very small chance; no chance at all.

catch hell

To be severely reprimanded, punished, or beaten.

chance upon

To find (someone or something) by chance.

Chinaman's chance

No chance; zero possibility.

cold day in Hell

The time of occurrence of an event that will never happen.

come hell or high water

Regardless of the hardships; no matter what difficulties may arise.