A Seattle baseball fan has become a social media sensation after creating a series of hilarious signs meant to mock the thousands of Canadians who showed up at Safeco Field to cheer for the Toronto Blue Jays.

Dan Carroll said as a life-long Mariners fan he felt obliged to push back after being overrun by rabid Jays fans from north of the border.

Blue Jays fans turned up in droves to watch their team play the Mariners in a three-game series in Seattle. (The Associated Press)

"The Mariners are a pretty big deal to me," said the 30-year-old. "To say the least, it's annoying to hear, 'let's go Blue Jays' in my house."

Estimates are Blue Jays fans have outnumbered Mariners fans two-to-one during the critical three game series in Seattle. Border crossings between the Lower Mainland and Washington State reported long waits due to the huge volume of Canadians heading south to the games.

This one didn't get released yet. <a href="https://twitter.com/BarackObama">@BarackObama</a> <a href="https://t.co/yqLnXLy72i">pic.twitter.com/yqLnXLy72i</a> —@tworsandtwols

Carroll showed no mercy with his felt pens, taking aim at the metric system, the maple leaf and — most gallingly— the inability of any Canadian NHL team to win the Stanley Cup in over two decades.

"I focused on the Stanley Cup sign because I figured I should know my audience and punch to the gut," he said.

More examples of Dan Carroll's Canada-mocking handiwork. (Daniel Carroll)

He even sought out a bilingual friend to help create a sign in Canada's other official language. Translated it reads 'This is the sign that we made to mock you in French.'

Carroll was a little miffed to discover not many Canadians in attendance could understand what it said.

"I guess French is not as big in Western Canada as it is in Eastern Canada," he concluded.

On Twitter, the posts of his handiwork have been seen and retweeted thousands of times. Carroll calls the attention he's received "very surreal."

The Blue Jays won the first two games of the series, improving their chances of making the playoffs and potentially ruining Seattle's.

Carroll posted his reaction on Twitter: