TALK ABOUT a tough crowd - Ross Inglis thought he had seen the toughest of the tough as he sat behind his piano one night this month on stage at a Niagara Falls dinner theatre.

 For his two hours as the portable orchestra for Oh Canada Eh?! - a variety dinner show full of songs and sketches that bleed maple-leaf red - Inglis was staring into a front row full of proud Quebecois.

 "They said afterward that they were all separatist," recalled Inglis, resting up with a Coke after the show. "All the French people sang along with Mon Pays.

 "They loved it. One of them said 'The pride you have in your country - that is what we have in Quebec.' "

 Inglis took it as high compliment. Tailored mainly to the tourist, Oh Canada Eh?! exceeds the expectations that accompany every new attraction in the city of wax museums and tacky T-shirt shops. After more than 50 shows, the show's producers claim to have not heard a single negative word. Shows in 1995 are already sold out. Outside the former office space that houses the show in Pyramid Place, tourist testimonials are posted on a bulletin board.

 The show is such an unusual sight - a visible, rousing celebration of Canadianism - that by its nightly climax, when the entire cast breaks into the anthemic They Call it Canada and the national flag waves from the back of the stage, surprised Americans in the audience are the first to jump up and clap along.

 "I don't think they had ever expected and had seen this kind of thing before," said Inglis, who was born in St. Paul, Minn. (a claim he makes quietly, having lived in St. Catharines for all but the first two weeks of his 24 years). "I've seen a few people leaving saying - joking - 'It's kind of American. It's patriotic.' "

 The show concedes its own hokeyness right from the top, when a couple of explorers - a Frenchman named Francois and an Englishman named Roderick - set foot on the unspoiled splendor of Canada and discover Trivial Pursuit.

 They put the game away, preferring instead to marvel at the possibilities of their new home.

"Zat is why I come to Canada, mon ami, wit' only my dreams... and my phony French accent," Francois swoons.

 Once longtime St. Catharines stage actor Jim Cooper - who developed the show with his business partner, Ross Robinson - takes over as the show's courboisier MC, the French-English split continues. Gilles Vigneault's Mon Pays and the stirring lament of exiled Canadians, Un Canadien Errant, trade off with I's the B'y that Builds the Boat and what might be the most popular song in the show, Gordon Lightfoot's The Wreck of the Edmund Fitzgerald.

 POPULAR FAVORITES that most people don't identify as Canadian, such as selections from the musical Hair and the old cowboy tune Tumbling Tumbleweeds, are included in a parade of more than 40 northern songs.