Definition: the leader or boss
Example: Roger was top banana at the office. Ironically, the office was responsible for banana sales across the Pacific Northwest.
‘Top banana’ originated in 1920s burlesque comedy, specifically in the use of the fruit as a punchline.
There is debate as to who the particular comedian was, with several names listed by several sources. It’s possible, that as the banana was relatively new at the time and very strange to the average person, it was used as a gag by plenty of Vaudeville performers.
The phrase first came to describe the performer at the top of the evening’s bill. The act listed below the headliner became known as ‘second banana‘. Both phrases are still used in the entertainment industry today.
The idiom later crept into more common usage. Now, people outside the entertainment industry can be described in terms of strangely shaped yellow fruit. Its a dream come true for all of us.