Tsumura of the Hungry March Band performs a trumpet solo in a spontaneous jam session after the second annual HONK! festival, which returned to Somerville and Cambridge this past weekend, ending on Sunday with a parade from Davis Square to Harvard Square. The festival is a celebration of activist street bands from all around the world. Seventeen bands from as far away as Italy marched the streets and held public concerts throughout the weekend. Sunday’s parade also featured the Bread & Puppet Theater and Car Talk’s Click & Clack, the Tappet Brothers.