Taken from Beth Lapides' page (more on her significance here) is this annotated video of Patton Oswalt at Un-Cabaret. The annotations dissect how, when asked questions about his anecdote, Oswalt's responses are not only funny but truthful and within his character. It's not so much that he's on. It's more like he's really present onstage.
In this sense comedy is like reporting: Patton Oswalt is giving the story while Lapides (the hostess who asks questions to elicit further information) is like the editor, demanding even a seasoned vet like Oswalt to give more detail and to answer any lingering questions.