This paper seeks to contribute to the understanding of ways in which language ideologies (Rumsey, 1990; Schieffelin, Woolard, & Kroskrity, 1998; Silverstein, 1979) and local discourse practices are exploited in the construction of linguistic expertise through an examination of the uses of humor in an Irish language class. Various forms of humor, including puns and formulaic jokes, rely on specific knowledge on the part of both teller and audience (Norrick, 1993, 2003) and thus have been referred to as a “short intelligence test” (Sherzer, 1985). In this paper, I examine the ways in which humor is used both to mitigate risks associated with displaying a lack of linguistic knowledge and to claim a variety of linguistic expertise that involves knowing about the language of study even without knowing a specific structure or vocabulary item.