In the gimmicky but enjoyable Mr. Saturday Night, Billy Crystal hidden, much of the time, under age makeup and a collection of hideous toupees plays an egomaniacal nightclub comic named Buddy Young Jr., the sort of obnoxious borscht-belt jokester whose one-liners should always be followed by cymbal crashes. Beneath his ''ingratiating'' show-biz patter, Buddy is a hollow gag machine; he has the personality of a particularly abrasive salesman. The character, which Crystal originated on a 1984 HBO special and did several times on Saturday Night Live, could be a synthesis of all the famous Jewish comics who flourished between the decline of vaudeville and the explosion of the pop '60s. Like Milton Berle, Buddy wields a stogie and flashes a phony, ya-gotta-love-me smile; like Jackie Mason, he's a self-destructive insultmeister who puts his Jewishness, and his contempt, at the center of his act; and, like Jerry Lewis, he has a streak of manic infantilism on some level he's still a kid making funny faces.
The premise of the movie is that Buddy is essentially the same pushy, hostile crank off stage that he is on. His compulsive joke telling is the only way he has of communicating. He's trapped in those jokes they're all he is. What they allow him to express, in barely disguised form, is the casual contempt he feels for just about everything: His genial brother/manager (David Paymer), his wife (Julie Warner) and troubled daughter (Mary Mara), his audience, and his own career, which keeps stalling because of ''bad breaks'' but really because Buddy can't put his derision on hold long enough to make it to the big time. Contempt fuels his act and poisons it. The very heart of his comedy is second-rate.
Directed by Crystal himself, from a script he cowrote with Lowell Ganz and Babaloo Mandel (City Slickers), Mr. Saturday Night is a perverse labor of love. Crystal knows what a lout Buddy Young is. It's also clear that he adores him for his loutishness for the crude vitality of it. I didn't laugh at many of Buddy's jokes, but I'm not sure we're really meant to. Crystal is paying tribute to a primal vein of American-Jewish humor, with its hyper fusion of rationality and ''craziness.'' Buddy's jokes are so raucous, so brazenly obvious (to a fat heckler: ''You look like New Jersey in pants!''), they just about transcend their own formula. We're listening to the Catskills equivalent of the Talmud.
The movie, which seems loosely inspired by the 1960 Laurence Olivier film The Entertainer, never quite escapes being a stunt. Crystal gives a terrifically inventive performance, but he still works like a sketch comic, creating Buddy almost entirely from the outside. We don't feel the worminess of Buddy's vulgar, stage-bound soul; even his hostility is a little quaint. And the movie sanitizes his behavior as well. (It manages to suggest that he's a philanderer without ever once showing him with another woman.) Still, there is such a deep love for show business in Mr. Saturday Night, such knowing affection for the way that Buddy's jokes emerge from both his Jewish-family background and his own screwy, neurotic personality, that the movie is very winning it's like a livelier, savvier For the Boys. Despite a heavy wash of sentimentality, Mr. Saturday Night never really asks us to like Buddy. Instead, it does something heartfelt and clever: It makes his very disagreeableness worth a tip of the hat. B+