“We aren’t one of those bands who put up an ad on Craigslist like, ‘Bassist needed; must love metal,’” says Prairie Spies keyboardist Evan Skow. The Spies got together almost by accident—Skow and singer Max Brooks didn’t even know guitarist Ben Fong, much less plan to form a band with him, when their mutual friend Bridget Love hooked them up as roommates in 2005. Of the six original members, only three had ever even been in bands before. But Love wanted to play in a band for her birthday party, and she talked the roommates into being in it—along with bassist Paul Guilianelli, whom she’d met at a party, and drummer Ryan Collins, who’d been in her MFA program at Columbia College. Calling themselves the Sharks, they played what they assumed would be their first and last show at Ronny’s in February 2006.

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But after the party, says Skow, “we just kind of kept doing it.” Nobody in the band had gone into it with a preconceived idea about what their sound should be, but what came out was scrappy, uncomplicated, punked-up pop. The joyously sloppy songs had plenty of hooks, but what made the Sharks special was their hyperactive playground energy—they had the we-don’t-give-a-fuck attitude of punk rockers, but without the nihilism.

But then last year the Sharks took a baby step toward legitimacy by recording an EP, which they released themselves on CD-R. Love had left the band in June 2007, a couple months before they recorded, so they decided to title the disc Bridget Quits. By turning it into a sort of tribute to their departing bandmate, though, they inadvertently gave themselves a reason to approach the project almost soberly. “I think it was conceived as a joke,” says Fong, “but once it became Bridget Quits it was, at least for me, a serious thing. It did signify a change in the band with her leaving, because she brought a really intense dynamic to the band. I kinda see it like a serious joke, almost.”

Surplus Enjoyment came out in May on Comptroller Records, also home to the Fake Fictions (and Boner Jams, which includes members of both bands and put out a CD last year in an edition of two). The Prairie Spies are currently on a nine-date tour to support the album—the first tour anyone in the group has been on—and they’ll stop at the Bottle for a free show on Monday. They plan to lose money on the trip, but they’re fine with that. They may not be quite as casual about the band as they were two years ago, but their primary reason for playing together hasn’t changed.

Mon 7/21, 9 PM, Empty Bottle, 1035 N. Western, 773-276-3600.F