Some play Brad as a nerd. Some play him as a misdirected jock. Sue Blane's original costume designs show him with a peace sign pendant; he may have thought he was a swinging cat.
First personified by Christopher Malcolm, then immortalized on celluloid by Barry Bostwick, who is still cool about it more than 35 years later. As Bostwick's said many times before, "That's Mr. Asshole to you!"
Sal Piro writes in the 1984 Audience Participation poster:
"Early 60s college type. Probably from the Midwest. Well-scrubbed, goes to church, voted for Nixon and buys his clothes at Sears. Look up "square" in the dictionary and it says, "See Brad Majors."
(This character is the prototype for anyone who has refined clumsiness to an art and enjoys walking around theaters in their BVD's.)"