Forget toilet paper. Whatever with paper towels. Cardboard tubes are for fighting: It's the civilized way to satisfy the deep-seated human urge to bash each other with sticks. Cardboard Tube Fighting League is new and delicate—the only way to keep it from degenerating into some kind of Renaissance Faire awfulness is to show up early, bring friends, and make this event your own. (Gas Works Park, 2101 N Northlake Way, 4—6 pm, $1.)