This weekend, there’s good reason to party like it’s 1999. SEE Crumble (Lay Me Down, Justin Timberlake) What: A sweet play about the tumultuous journey of a mother and daughter getting over a death in the family. Why: Cry us a river. When: Nov. 4-Dec. 10; Thurs.-Sat., 8 p.m. Where: La Val’s Subterranean Theater, 1834 Euclid Ave., at Arguello Blvd., Berkeley (510-464-4468). Purple Rain What: Sing along to Prince’s infamous movie. Why: U would die 4 him. When: Fri. & Sat., midnight. Where: Bridge Theatre, 3010 Geary Blvd., b/t Blake & Cook Sts. (415-751-3213). HEAR Jacqui Naylor at the San Francisco Jazz Festival What: Local music darling sings jazz classics over rock tunes and vice versa. Why: And all that jazz. When: Sun., 2 p.m. Where: Legion of Honor’s Florence Gould Theatre, 34th Ave., at Clement St. (415-788-7353). EAT Bakesale Betty What: Sticky date pudding, banana bread, and lemon bars at Aussie’s new outpost. Why: Get baked. When: Sun., 7 a.m.-2 p.m.; Mon., 7 a.m.-4 p.m.; Tues.-Sat., 7 a.m.-7 p.m. Where: 5098 Telegraph Ave., at 51st St., Oakland (510-289-5505). BUY Native Plant Sale What: Get help picking out flora that were literally meant to grow in your backyard. Why: No green thumb necessary. When: Thurs., 7:30 p.m. Where: County Fair Building, 9th Ave., at Lincoln Way (415-752-7031).