A simple St. Patrick's Day promotion from a Vancouver eatery has left beer drinkers around the world foaming at the mouth.

The reason? Its depiction of one very poorly poured pint of Guinness.

Railtown Café posted the advertisement, which features an overflowing beer next to a plate of finger food, on its Facebook page this week, drawing immediate scorn from far and wide.

It even made international headlines, with Irish website The Daily Edge scoffing that "A Canadian Café is using *this* pint of Guinness to advertise its Paddy's Day party."

Some social media users felt the pour was so bad the eatery must have done it on purpose to drum up publicity. Others seemed nothing but mortified.

"Every person in Ireland collectively screams in horror," one Belfast resident wrote on Twitter.

What armchair critics might not understand is that it's not easy to pull a pint of Guinness; there's a real science to getting the perfect pour.

According to the company, pints should be tilted at a 45-degree angle and filled three-quarters full, then left for 90 seconds while the beer settles.

"We always go by eye. You want to get it to where it's just very lightly brown [at the top] and dark at the bottom," said Darren Pierce, bartender at Irish Heather in Gastown. "Then we're going to leave that up there to cascade."

Glasses are then to be filled to the top, leaving just the right amount of head before they’re sent off to thirsty customers.

Railtown Café pulled down its advertisement following the online outcry, and has replaced it with another image featuring an improved pour.

"Thanks for the friendly comments, everyone!" the eatery wrote. "We’ve poured another pint that we hope is worthy of Ireland."

The eatery also offered an olive branch to Irish customers, promising a free pint on Friday for anyone with a valid passport from the Emerald Isle.

With a report form CTV Vancouver's Ben Miljure