Walter F. Berman is a school friend of Stephanie Tanner. Walter was a student in Stephanie's second grade class who was teased many times because of his resemblance to a duck. Many kids in his class teased him in different ways, like calling him "Duckface", making quacking noises around him, and even throwing bread at him.
When Uncle Jesse found out that Stephanie was part of teasing Walter, he forced her to call him, telling her that being teased wasn't fun. After Stephanie called him, he was led to believe that she liked him. He considered the both of them together, as boyfriend and girlfriend. Stephanie, who did not want to be "with" him, told him that they would have to keep their relationship a secret.
On a day where both Walter and Stephanie's friends came over to her house, she was teased for being in a "relationship" with Walter, being called "Mrs. Duckface". She stood up for Walter and herself, telling the other kids about the times that they were teased, and how they didn't like that. Eventually, Walter and Stephanie were considered "just friends".
He appears in three episodes, all in season three: "Nerd for a Day", "Divorce Court", and "Mr. Egghead". He is also mentioned in two other season three episodes: "Misadventures in Babysitting and "Our Very First Telethon".