While there isn't a specific theory put forward in this great collection of humorous autobiographical essays, the common denominator in a lot of them is references to difficulties in speaking and communicating clearly.
For example, some of the essays cover the awkward moments Sedaris had at school during a time in which he was struggling with a lisp, which the school's speech therapist was attempting to help him with this. Sedaris notes with a touch of irony that while a number of kids were embarrassed by being called out of class for speech therapy, it never seemed to bother the popular kids.
Later in the collection of essays, another anecdote about language comes up when the author starts teasing his brother, Paul, about how much he swears.
Later still, when Sedaris relocates to Paris, he finds much humor in his attempts to become more proficient in French and admits to spending way more time than he would have liked watching dubbed American movies while in Paris. Again, this links back to the theme of words, language, and communication.
The title of this collection of essays also adds credence to the theory that language can lead to challenges. The phrase "me talk pretty one day," while understandable, is not a correctly worded phrase or sentence, and is the type of thing you would expect to hear from a young child just learning to use language to communicate his or her ideas.