Chance High

To reach a point of being so fucking high on acid, that you need to be in your room immediately. It doesnt matter how far you are from your room either, all thought and reason dissolve when you reach this point. You usually spend the rest of the night hearing terrifying sounds.

Man i need to be in my room - Friend One
Dude we're at the lake and i'm high on LSD - Friend Two
I need to be in my room now - Friend One
You're Chance high, you shouldn't have taken two tabs of that shit - Friend Two

Dude lets take a chance and take three tabs of LSD - Guy who wants to get Chance high

High chance

Its Low chance but opposite.
When something has a big possibility to happen.
As if something that you don't or do want to happen has a lower chance then when something other.

There is not a high chance that you are seeing this.