A chillbrah is the final, black-hole like phase an otherwise interesting person can fall into. Initial signs of brah-ism are the first signs (usually, hanging out with hairy/lame friends who smoke a lot of weed) of becoming a chillbrah. Once the brah infection takes over, a person is still capable of doing awesome things and participating in adventoires, but only when not occupied with their brah friends.
Final phases of chillbrah syndrome happen when the chill, loosely translated as the "fucking boring," phase sets in. This is characterized by being less intense, not caring about things, and responding to most questions with "yeah, it's/I'm chill." Once taken by chillbrah syndrome, a person is lame and hangs out with their boring, lame friends to smoke weed and try to have sex with any moving target with a high blood alcohol level. A chillbrah should not be invited on an adventoire or it will become shitty.
Though there is no known recovery from becoming a chillbrah, efforts may be taken to prevent a loved one from transitioning into the even more debilitating chillbrahchill.
David used to be so intense and awesome before he turned into a chillbrah. Now all he does is drink beer, get fat, and try to date rape underage girls.