In Manhattan's Blue Angel last week, the house lights dimmed and the M.C. announced the newest thing in the nightclub belt: a theoretical physicist who turns out tunes on the side. Tom Lehrer, tall, lean, 25, strode purposefully to the piano, peered into the crowd through horn-rimmed glasses, and launched into what Variety called "a comedy of terrors." He would, he said, sing an "ancient Irish ballad, written a few years ago." He turned to the keys, drummed out a melancholy accompaniment, and in a sardonic voice began to sing. Sample lyric:
About a maid I'll sing a song
Who didn't have...