this is one of my favorite scenes from a great Bob McKimson cartoon.
Back when I worked at the ultra-conservative and bland Filmation studio, we used to play the audio of this clip over the intercom in the middle of the day to remind all the old guys of when cartoons were funny.
I love the idea that a little guy can be menacing, just through the sheer power of his psychosis.
"Birth Of A Notion" was made near the beginning of what I think of as McKimson's Golden Age - 1947-1949. He made a lot of great cartoons, especially in that period.