Jim Gaffigan has a wildly successful career as a standup comic, more than a million Twitter followers, and his just released first book, Dad Is Fat (Crown), offers his take on everything from cousins (“celebrities for little kids”) to growing up in a big family (“I always assumed my father had six children so he could have a sufficient lawn crew”) and changing diapers in the middle of the night (“like The Hurt Locker, but much more dangerous”).

Being a father was never on Gaffigan’s to-do list. Happy with the nomadic, nocturnal life of a standup comedian, Gaffigan always imagined his future as “that weird uncle who lives in an apartment by himself in New York and everyone in the family speculates about.” But all that changed when he married “someone who gets pregnant looking at babies.” His wife, Jeannie, is now his partner not only in parenthood but comedy. “We write everything together. Not only can she fill in the holes in my knowledge of grammar, she’s really funny.”

Gaffigan and his family live in a two-bedroom fifth-floor walkup in Manhattan—a story in itself. “We don’t plan to stay forever. But it’s hard to move with kids, and you don’t want to move when someone’s pregnant, and my wife’s been pregnant for about eight years.”

With five kids, it’s not surprising Gaffigan has what he calls “an unnecessary knowledge of good children’s books—I’ve read way too many Fancy Nancy and Angelina Ballerina books. You’re always so excited when a kid’s engaged by a story, but once you’ve read something a thousand times... I can now recite Good Night Moon from memory. I used to read a book a week, but at this point I’m just thrilled to get through an episode of Damages on Netflix.”

When it came to writing his own book, Gaffigan was “terrified I would hate the process of writing—I’d heard stories about people who found it so hard they wanted to give their advance back. But I really enjoyed it. There was a sense of accomplishment in completing it and doing it for the right reasons. And the fear of doing a bad book was really motivating for me.”

Today at noon, Gaffigan is doing a q&a and signing copies of Dad Is Fat at the Downtown Stage.