Justin Bieber Booed At Montreal Concert For Dissing Canadiens, Shouting Out Leafs

Justin Bieber might need a lesson in "know your audience" ... 'cause fans booed the hell out of the singer during his tour stop in Montreal on Tuesday for dissing the hometown Canadiens.

Bieber -- a MASSIVE fan of the Habs' hated rivals, the Toronto Maple Leafs -- showed love for his team right before his final song of the night ... saying, "How about those Leafs though, huh?"

The "Ghost" crooner even gave a shoutout to his close buddy for scoring a goal against the Canadiens on Saturday ... saying, "Auston Matthews is really doing some work here in Montreal."

Of course, the Canadiens are hot garbage this season ... sitting at the very bottom of the standings with an 18-38 record, despite beating the Leafs over the weekend.

Biebs made sure to let the crowd know he was well aware of their struggles this season ... adding, "How's that playoff spot looking for you guys this year?" and "Maybe next year, maybe next year."

The fans weren't having it -- letting the boo birds fly and even shouting expletives as Bieber continued to diss the hometown team ... even starting a "Go Leafs, Go" chant.

The stunt comes one week after the Leafs debuted their Bieber-designed Drew House jerseys ... which they wore on the ice for their Next Gen game.

Bieber eventually got real and stopped the trolling ... saying Montreal is truly one of his favorite places to perform in the world.