“We were just kids/freaking out” sang Beastie Boys ’ Mike D last night to about 150 people inside Los Angeles’ cash-only gay dive bar The Plaza Nightclub & Dance Hall. He dropped the line toward the end of his first of four rare and intimate solo shows , his voice drenched in reverb — so much so that it was hard to make out his vocals — and felt like an appropriate sentiment. While Mike D performed mostly new songs from an upcoming album, he still found nostalgia for his old band’s classic,