This paper investigates plays on words involving conversational implicatures or hidden meanings in short stand-up comedies by a Japanese duo. It is observed that regular patterns of wording exist in such conversational exchanges which cause the audience to laugh. Those patterns are typically composed of three parts: subtext, punch line and follow-up, and they appear in that order. Each part is allotted a particular function: the subtext carries an implicature, the punch line reveals it to make the audience laugh and the follow-up explains or summarizes the punch line. The duo induces the audience' s laughter by intentionally betraying or flouting people’s natural assumption or implicature resulting from the conversational flow. Such violations and varieties of irregularities can be explained using H.P. Grice' s theory of the cooperative principle and maxims of conversation. Various violations are successfully analyzed in terms of Quantity, Quality, Relation, Manner, or the multiple effects of these using Grice' s framework of conversational maxims.