To set the record straight, a beaster is an individual who lives life with no limits. Specifically, it pertains to a person who on a daily basis, or at least on weekends, consumes three or more tall cans of malt liquor in an evening and smokes all the dank that is handed to them.
An individual whose placid exterior hides a savage beast within. Such individuals tend to work in staid corporate atmospheres and terrorize fools with a mastery of white collar arcana. Approach beaster at your own peril.
A party held on the Saturday before Easter. Usually involves drinking Beast (Milwaukee's Best) and a Beaster Egg hunt:
Hidden cans of beer that you must finish before moving on to the next, or bottles filled with mystery beers and shots that are numbered, so at the end you can find out what you drank.
This tradition originated in Berks County, Pa in 2003.