A popular acronym in butch/femme lesbian subculture. OFOS stands for "Old Fashioned, Old School". Refers to a relationship which follows traditionally heteronormative roles.
In addition to the usual feminine or masculine visual signifiers of butch/femme relationships (clothing for example), OFOS couples embrace old fashioned social behaviors such as chivalry, etiquette and courtship rituals.
The gentleman butch brought her lady roses, offered her arm as they walked to the restaurant and ordered for her once seated. And the femme knew she was the luckiest lady on earth to have found a true OFOS butch.