The last time they co-hosted a Camp Freddy rager here in D.C., campaign operatives John Murray and Doug Davenport drew an enthusiastic crowd that partied hard, rocked out and kicked in $70,000 for the military-rehab-minded folks at Rivers of Recovery.

The duo are now hoping to sell out the 9:30 Club (815 V St. NW) by dangling the free-form super group and a timely excuse for cosplay in front of those who wouldn’t dream of missing the “2nd Annual Bipartisan All Hallows Eve Costume Party.”

The show is scheduled to take place at 8 p.m. on Oct. 26. General admission tickets start at $50 — or you can spring for a VIP sponsorship package, which includes access to an open bar, semi-private breathing room on the cordoned off second floor and a meet-and-greet with the featured performers — with all proceeds flowing through to the Boulder Crest Retreat.

And there will, of course, be a costume contest.

“This is an opportunity to come together, have some fun and help those who have given this country so much,” Murray told HOH, adding that they hope to pull off the charity concert, shutdown or no. “We can’t predict what will be happening later this month, but we think some Halloween good cheer might be just the thing everyone in this town needs!”

Camp Freddy didn’t perform at last fall’s shindig, a sold-out affair held at Hill Country, but they did blow through town in the spring of 2011 to assist in Murray’s and Davenport’s first philanthropic effort.

“I think it is safe to say the funniest thing I saw was backstage when Sebastian Bach (Skid Row) and Sully Erna (Godsmack) got into a discussion about the cupcakes in the band room. Sully remarked about how much he loved them and Bach responded, and I am paraphrasing, ‘Yeah, I don’t eat cupcakes any more because it gets me invited on to those celebrity fat guy shows!’” Murray said of the surreal encounter.

Davenport had his own out-of-body experience while escorting the rockers around 1600 Pennsylvania Ave.

“Especially when I took them to see the ‘flower’ room at the White House … total non-D.C.-typical stuff for sure,” Davenport shared via email.