"Sexual Intercourse" failed to tie "Gemberling's" record for "longest-running show," but it set another: "longest-running show to never reach #1." And perhaps nothing sums up "SIAS" better than that. It was a niche show, with a core of devoted followers who kept it going for a long time, but it lacked the mass appeal to catapult it into "Shutterbugs" territory. But sometimes, that's what characterizes true art. And "Sexual Intercourse: American Style" is art. In this episode: A crooked Senator's aide threatens to end the Baby Birds. Less