Chanticleer's boastfulness is also humorous because it is so blind. He is so focused on his own accomplishments that he is completely oblivious to the fact that he is being made fun of. For example, when the other animals hear him singing, they all laugh at him. But Chanticleer doesn't even notice. He is too busy admiring his own voice.
Chanticleer's boastfulness is a classic example of the comedic trope of the "boastful fool." This type of character is always bragging about their accomplishments, even when they are not true. They are so convinced of their own greatness that they are completely oblivious to the fact that they are being made fun of. This type of character is always a source of humor, and Chanticleer is no exception.