Montreal trades Patrick Roy to Colorado for a bunch of nobodies.
The Montreal Canadians were the most successful team in NHL history, winning at least one Stanley Cup in every decade from the '10s to the '90s. One of the biggest reasons for their success in the 1980's and mid 90's was goaltender Patrick Roy, who besides having a name that is impossible for an American to pronounce properly, was arguably the best in the league at his position, and had led Montreal to Stanley Cups in 1986 and 1993. But after a highly publicized confrontation with his coach in 1995, Roy was shipped off to Colorado for three dudes even hockey fans had barely heard of.
Why the trade was so dumb: For starters, Roy, like Robinson, led his new team to a championship in his first year there, and would go on to win another. Montreal, on the other hand, couldn't find a regular goalie for another 5 years, and their fans refer to the Roy trade as "Le Trade." When a trade is so dumb that your fans go, "ah, merde, Le Trade, that sucked beaucoup" without even needing to specify which one, you don't need a nuanced understanding of the sport to know it was pretty dumb.