It’s the 21st anniversary of the formation of Portland’s premier marching band MarchFourth and over years of high energy shows and steady touring, this now 15-person line-up has forever minted its legacy as the dance show to go to as though the circus is in town. They’ll be spiking up the tent, so to speak, at Humbrews tonight at 8 p.m., and if you haven’t seen the show yet, you’re in for the treat. If you already know, I’ll stop jabbering. ($30, $25 advance).