Answer:
The verbal irony adds some humor to the scene.
The verbal irony shows the audience that Casca is easily led.
Step-by-step explanation:
According to a different source, this is the passage that comes with this question:
CASCA. Let us not leave him out. CINNA. No, by no means. METELLUS. O, let us have him, for his silver hairs Will purchase us a good opinion, And buy men’s voices to commend our deeds. It shall be said his judgment ruled our hands. Our youths and wildness shall no whit appear, But all be buried in his gravity. BRUTUS. O, name him not. Let us not break with him, For he will never follow anything That other men begin. CASSIUS. Then leave him out. CASCA. Indeed he is not fit.
In this passage, we learn that Casca originally wants Cicero to join the assassination plans, but that Brutus convinces him that Cicero should not join them. The fact that Casca so easily changes his mind provides some humor. It also shows the character of Casca, and how he can be easily led by others when necessary.