Didja hear the one about the comedian who defected?

`YAKOV,'' someone from the audience calls out, ``did you enjoy freedom of religion in Russia?'' ``Absolutely,'' says the man on stage, ``you could worship any way you wanted to, as long as you didn't disturb the other inmates.''

``But what did you do for fun over there?''

``We defected.''

Such gags are typical of Yakov Smirnoff, whose devastating brand of humor has been showing Americans just how potent a weapon comedy can be. In the nine years years since he emigrated to the United States - with $100 in his pocket and speaking no English - Mr. Smirnoff has become a unique figure on the American pop-arts scene: a nationally known ex-Soviet comic.

Although now a familiar film and TV performer - most visible in the first-run syndicated TV comedy series ``What A Country!'' - Smirnoff hits a comedy peak during his stage and nightclub monologues. These are masterfully delivered to responsive audiences who roar with delight as he launches intercontinental gags about the Soviet government and the rigors of Russian life.

A full-bearded figure in dinner jacket, Smirnoff speaks into a hand-held mike - eyes agleam with wicked relish, deadpan face harboring a crafty grin, voice a reflective monotone. During the act I caught in a large auditorium in nearby Lynn, Mass., a Boston suburb, Smirnoff reached into the wellspring of his Russian past for jokes that were sometimes just this side of a shudder. And as he recounted his early days in the US, the house rocked at the ludicrous image of the hapless innocent who misunderstood signs on food boxes in supermarkets inviting him to ``Try this!'' - or who grew exasperated at newspaper ads that mocked him by announcing a ``Big sale - last week.''

In Smirnoff's sardonic hands, this kind of material causes a comic shock of recognition that leaps across oceans and ideological barriers. But it's an old comedy trick, of course - showing listeners how absurd the familiar can seem through the eyes of a newcomer. So I couldn't help asking - when we chatted after the show in his hotel room - if these stories about the Soviet Union were primarily a comedy routine.

``No, 90 percent of the material actually happens,'' Smirnoff answered, sitting on his bed and leaning back against the headboard, ``but it's exaggerated, as any comedy is. And a lot of it has to be based on the perception Americans have of Soviets. Those are stereotypes, but they exist.''

But doesn't he ever have misgivings about making fun of his mother country? ``No,'' says Smirnoff. ``What you see on stage sounds like I'm making fun of them, but I never really cross the border line. There are certain things I have in my mind that I don't talk about - except when I do a lecture, for example, in a college. But I don't think the funny side of me can hurt the Soviet Union and I don't think they're worried about it.

``And I feel you also see the good side of the Soviet Union - a nice guy, well dressed, smiling. So you are getting a pretty balanced package, not just an angry man who has a hammer and sickle in his hands and is trying to prove something. You're seeing a likable guy who is saying, this is what's funny.''

When Smirnoff first arrived in the US, he had no plan to target the USSR in his comedy. His primary motive was to get away from Russia. After growing up in the Ukrainian city of Odessa - where he says his favorite childhood game was ``Hide and Stay Hidden'' - he became a top comic in Russia, eventually signing on board Soviet cruise ships on the Black Sea as an entertainer.

By that time he was making more money than doctors and lawyers in his country, but he wanted out:

``I met a lot of tourists from different countries who were much happier than Soviet tourists were,'' he explains. ``They were open and would talk to you without worrying. Soviet people were constantly conscious about somebody watching them. Then I met a couple from Australia that spoke some Russian, and they told me they were going around the world. I said to myself that one day I'd be free enough to go around the world. It was weird, because all these people could have fun and then leave, and I was feeling like I was in a cage.''

Once in America, Smirnoff got a job as a busboy at Grossinger's, the renowned resort in that legendary heartland of comedy, the Catskills. He was armed with little more than an outlandish idea: to become a comedian in his new homeland.

``People would look at me like, `You're crazy. You don't know anything about this country. And you'll be going against big names.' And my roommate said, `Come on, there are so many comedians out there.' But then he stopped and said, `But there was never a Russian comedian.'

``I thought to myself, `No Russian comedian! Oh, good!' And that was the beginning.''

Watching the comics work at Grossinger's was ``like a crash course in America,'' Smirnoff says. ``Comedians are always hitting the topical notes that are on everybody's minds. At first I was watching them without understanding what they were doing, but the timing sounded very similar to what I used to do, and I started to understand a few words here and there. I put together some jokes, asking my friends lots of questions.''

The first time out on stage he knew little more English than the jokes he'd memorized, but it was enough to start with. Later came what Smirnoff calls ``a series of small clubs, and a lot of rejection, the kind every comedian goes through.''

But there were bright spots, like the New York club Catch A Rising Star. And when he moved to Los Angeles and performed at the Comedy Store, Smirnoff's media career began.

``More and more producers started discovering me,'' he says, ``and things started going my way.'' Roles in films like ``Moscow on the Hudson'' and ``Heartburn'' and guest spots on prime-time network comedies followed.

Does Smirnoff think there is really such a thing as a national style of comedy, something peculiar to one culture?

``I think comedy is very universal,'' he says, ``but in this country you have lost the storytelling that used to happen from door to door and from person to person. Today people don't tell many jokes to each other, because you can turn on the TV and see the freshest material about topical humor. In Russia, they still do it, because they don't see that much of it on television....''

But according to Smirnoff, at least one American still has the storytelling touch: President Reagan. Smirnoff says he discovered this when he found himself playing Can You Top This at a private party attended by the President last January.

``The moment he caught my eye, it was me and him back and forth with the jokes,'' Smirnoff recalls. ``There were some senators and ambassadors and stuff, and they were saying, `Mr. President, tell him this one, tell him that one.' I had to respond to every joke they would come up with. The President is a wonderful storyteller and loves to tell jokes the way people used to. I had to work real hard to keep up with him. That's the old style of entertainment.''

Later, Smirnoff says, he was invited to do his act for the President and a large gathering at another function. Not bad for a little Russian boy who used to play ``Hide and Stay Hidden'' on the streets of Odessa.