When St. Peter has opened the book of Beavis' life to the page titled March 2, 1992, he says "on the 3rd day of the 4th month of your 12th year" (this makes him 11), making Beavis' date of birth on or about November 28, 1980.
Has been released on "The Final Judgement" VHS tape, the time life DVD re-release and "The Mike judge collection Vol. 1".