“Dichotomy” might be the best way to think of San Francisco band Happy Fangs. There’s the duo’s name itself, which, although it won’t earn awards for best band moniker anytime soon, does accurately reflect the sort of vicious party energy encapsulated in its pop songs. Then there’s singer Rebecca Gone Bad’s powerful voice, which is at once sassy and girlishly innocent. Coupled with guitarist Mike Cobra’s raucous, distorted licks, the band’s songs — as heard on its debut EP, released earlier this year — are the kind that simultaneously induce dancing and headbanging. The duo completes this dualism visually, dressing in black and white and wearing black and white face paint. It might seem a bit obvious, but it’s worked: The band already played CMJ and just landed a slot in next year’s Noise Pop festival. See it at Cafe du Nord (2170 Market St., San Francisco) this week, when it plays with Beware of Darkness with Down and Outlaws.