Gimme a Break! - Season 6 Episode 12

Nell decides to buy a Christmas tree, as does Addy, who both know that it costs too much for one in New York. As the gang begins to celebrate Christmas New York style, Joey tells Matthew that there is no such thing as Santra Claus, and Nell blames Marty for the whole thing. In the end, Nell realizes that Marty always didn't believe in Santa Claus because he never got the toy train he saw in a store window when he was a child. In the end, Nell invites him to Christmas dinner, and on Christmas morning, he is surprised to see the toy train he has always wanted, which both Addy and Nell say they didn't get for him. Thus, proving to both Joey and Matthew that there is a Santa Claus afterall.