"Who would have thought one little chalkboard would cause such a stir?" That's the question asked by the proprietor of Handsome Her, a vegan cafe that gives priority seating to women — and gives men a chance to pay an 18 percent premium, citing a gender pay gap.

First, the details: Handsome Her opened for business on Friday in Brunswick, Australia, a suburb north of Melbourne. The "man tax" is optional, says cafe owner Alexandra O'Brien, and proceeds go to charity (benefiting Aboriginal women's services, according to Australia's ABC). The tax would also only be promoted for one week each month.

Despite a spirited discussion on social media (sample: "If it was the other way around there would be riots in the streets!!!"), the shop reports positive reactions from customers.

"We've had men travel across town to visit us and pay 'the man tax' and throw some extra in the donation jar - guys, you're pretty neat," O'Brien wrote on the cafe's Facebook page Sunday.

The proposal made a splash on social media after Paige Cardona, a friend of O'Brien's, posted an image of the chalkboard on Twitter. In it, Cardona sought feedback on house rules for a "space by women, for women" that included priority seating for female customers and a charge for male patrons that it linked to a 2016 federal report on Australia's gender wage gap.

By the time Handsome Her made its debut, the proposal had generated both discussion and publicity.

Customers packed the cafe on Friday and Saturday, according to its Facebook page.

O'Brien said that in addition to opening the cafe, she and her staff had also "gotten Australia talking about the long forgotten gender pay gap."

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