To relax and party as a means of celebration.
We're going to go to my house and chillibrate since that exams are over.
When one or a group has the need to celebrate an event or accomplishment but has recently celebrated in the form of alcohol consumption and finds it necessary to have a relaxed celebration, ie "chill".
Yeah man, last weekend was a little crazy, but like since I got in William and Mary we needa chillibrate this weekend.
Chillibrate for our liverates.