Tonight, head to the Middle East downstairs for Speedy Ortiz, Downtown Boys, and Ursula to benefit the Girls Rock Camp, a worthy cause if ever there was one. Not sure any of these bands really need an introduction, but just in case, here’s the rundown: Speedy are one of Boston’s flagship bands. Hardly anyone the world over makes music this heavy and catchy. Downtown Boys own the stage with their brand of uncompromising punk, and Ursula get things started with caustic ear candy that doesn’t give a howling hoot about you or any of your bullshit. If the music wasn’t enough reason to attend, you get special perks if you tack a couple bucks onto your ticket price in the name of girls rocking out: custom Speedy Ortiz nail art, posters, and if you’re feeling especially generous ($42 worth of generous), a Girls Rock Campaign print. Nail art as merch is only one of the more minor examples of artistic innovation you’ll see tonight.