It is a literal fusion of the words in the term:
'Dead Chilling'
Also meaning very relaxed, possibly, high.
An abbreviated version is: Deg (pron. dej, similar to veg)
A made up game of quarters with three cups arranged in a triangle. The rules are unknown because the inventor of the game, Brett Kavanaugh, could not explain them under oath.
"Hey Renate? Want to play devils triangle with Mark and I?" Brett asked.
A deal that is made by a person to another person to get themselves or someone something that they want but has negative effect on the person who made the deal because of the deal. Can also be used literal context of making a deal with the devil.
This is well know in multiple cults and religions.
Person 1: Hey dude my girl said I can hang around with you but i have to go shopping with her after, it was part of her deal.
Person 2: Ouch dude, thats a devils deal right there.