Moving East from Chicago in 2004 meant inevitably long hours for staffer Sean O’Brien and no time for his favorite pastime: improv comedy.

The Windy City is a legendary breeding ground for funnymen, and O’Brien studied with the storied Second City and Improv Olympics troupes.

“When I moved out here to D.C. to work for [then-Rep.] Rahm Emanuel [D-Ill.], I kind of let all that drop,” O’Brien said.

That is, until he heard about the Capital Fringe Festival, the District’s yearly celebration of alternative theater.

“I volunteered to do a little one-man show thinking they would give me 15 minutes or so. Instead they gave me 45 minutes and my own theater to fill up,” he said. “If it wasn’t for the festival, I wouldn’t have gotten back on stage.”

The show became “McSwiggin’s Pub,” a part-improv, part-scripted comedy about a night out at a local watering hole. Several of its first showings in 2008 and the follow-up performances last year sold out.

Now chief of staff to Emanuel’s successor, Democratic Rep. Mike Quigley, O’Brien will reprise his one-man show for the festival’s fifth anniversary.

This play has expanded to fill an hour and will feature O’Brien in the roles of an Irish bartender, a disgruntled tea partyer, a Hill staffer, a lobbyist and a House subway operator.

“This town is an absolute fountain of material. Every day the headlines bring something new that’s absolutely ridiculous,” O’Brien said. “It’s a great format because if there’s something in the headlines that day, I can incorporate it.”

And don’t expect him to hold back: The show carries a “not recommended for kids” rating on the Fringe Festival’s website.

“It’s a vehicle for me to deliver rants on the various news of the day,” he said. “It’s cathartic, it’s great. It’s like therapy.”

The remaining showings are July 15 at 10:15 p.m., July 17 at 10:30 p.m. and July 21 at 10 p.m. at the Goethe Institut (812 Seventh St. NW).

O’Brien’s performances are just a single element of a festival that is renowned for its oddball productions: Titles such as “My Christian Penis,” “DARFUR: The Greatest Show on Earth!” and “Do Not Kill Me, Killer Robots” grace the three-week fete.

But that’s what’s great about Fringe, said Michael Wright, who is directing the first D.C. production of Edmund White’s play “Terre Haute.”

“It opens up the venues in the area to productions that are unfiltered,” Wright said. “Fringe will not say, ‘Based on that content, we don’t want to do your show.'”

This year’s fest is the largest yet, with 137 shows being played out in 715 performances at 13 venues. And of course there’s plenty of prime fare for political junkies.

“Terre Haute,” for instance, is based on Gore Vidal’s Vanity Fair article about his correspondence with Oklahoma City bomber Timothy McVeigh.

White, an iconic gay author who has recently started moving into drama, imagined a series of fictional death row meetings between characters based on Vidal, the acclaimed novelist, and McVeigh, the domestic terrorist.

“While this isn’t a gay play, there’s some innuendo and one of the characters is gay and there is a physical attraction between” the characters, Wright said. “White had hoped that thinking about these characters in terms of their intimacy would raise questions about how they relate to the world.”

Over the course of their conversations, the two men realize that they have much in common, including a belief that the government is trampling the Constitution.

“Considering who the characters are in this play, there is still a tenderness that suggests that humanity exists in monstrous people,” Wright said.

The play shows nightly at 7:30 p.m. Thursday to Sunday through July 25 at the D.C. Arts Center (2438 18th St. NW).

A full schedule of productions can be found at capfringe.org.