Another way of saying, "not cool" or "god damn lame." Usually used during a fit of rage brought on by a situation where one is pwn3d.
(When grandpa Vince is taking a massive poo)
Timmy: "Grandpa, there's no more toilet paper."
Grandpa Vince: "Not chill!!!"
When a person tries to control everything around them because they need to be the center of attention. No one likes them because they play people and just dig themselves into a hole. They also lure people in with false promises and lies then throw them away like garbage. Most people who are not chill are usually ousted from societies and end up running away to other parts of the country because they realize no one likes them.
Guy: Yo last night i was hangin out with this chick Amanda, u know her?
Guy 2: Duddeeeee Amanda is soooo not chill, no one likes her.