Although I am not sure that I would characterize Mercutio as the "comedian" in 3.1, he is definitely the master of word play. While Romeo uses flowery, romantic rhetoric, a clever turn of a phrase will identify the speaker as Mercutio.
As evidence, see 3.1.15-30, in which Mercutio wittily characterizes Benvolio as an incorrigible arguer, one who would quarrel "with a man that hath a hair more,
or a hair less, in his beard, than thou hast," and calling him "as full of quarrels as an egg is full of meat, and yet thy head hath been beaten as addle as an egg for quarreling." The entire speech is full of sharp but clever jibes like this one.