Not have a snowball’s chance in hell
Definition 1 of 1
Pro Tip 1/3Strong Improbability
Emphasizes that something is extremely unlikely to happen, often adding a dramatic effect. 
I don't have a snowball's chance in hell of winning the lottery.
Pro Tip 2/3Informal Tone
Used in casual conversation, not in formal settings due to its mention of 'hell' which may be inappropriate. 
She doesn't have a snowball's chance in hell of beating me in a race.
Pro Tip 3/3Humorous Hyperbole
Often used to inject humor into a situation by exaggerating the lack of possibility. 
You're buying a sports car? With your savings, you don't have a snowball's chance in hell!