Explaining his collaborations with developmentally disabled performers, theater-maker Robert Wilson's eyes filled with tears as he noted such performers' "inability to lie." A similarly awesome purity runs through the work of singer-songwriter Daniel Johnston, who's not disabled, just bipolar, with his gorgeously simple lo-fi melodies cradling ballads about the battles in his heart and mind. Come laugh, cry, and wince along with an American treasure who doesn't know how to fake it. Perfectly selected opener: the one and only Kimya Dawson. (Neumos, 925 E Pike St, www.ticketswest.com. 8 pm, $18, 21+.)