In 1959, Yellen attended the fiftieth anniversary reunion of his high
school graduating class. As the writer of such standards as "Happy Days
Are Here Again," "My Yiddishe Momma," and "Ain't She Sweet?," he was
the class celebrity. The only unimpressed person was his former English
teacher, who upbraided him with, "So you're the one who wrote that
'Ain't She Sweet?'. And I thought I tought you that 'ain't' is bad
grammar!"