Once, he was simply Dean Martin's sidekick, a rubber-faced joker inexplicably beloved by the French. And for the past half-century, Jerry Lewis has championed the cause of curing muscular dystrophy and related diseases by asking the American public to pledge money every Labor Day weekend. Lewis started hosting his telethon--a 211/2-hour variety show (shortened this year to six hours)--in 1966. Since then, it has raised more than $1 billion. But after decades of health issues, including back problems stemming from his old onstage antics, Lewis, 85, will host his final telethon in September. In closing, he'll sing, as he always does, "You'll Never Walk Alone," now considered his signature song.