meaning; relaxing in a cold domicile, later it became a standard reply for just relaxing at home or being at ease where ever one was.
An ebonics term from the 70's that came from the "hood". Mostly used in the neighborhoods called the "Projects"
when the bills were not paid and the gas and electricity was turned off. During winter or when it was cold, when someone would call a person on their cell phone and ask "whatzup" the other person would respond with "we're just chillin"