Pi Pizza, the recently opened brick-and-mortar home of the popular food truck that’s a collaboration between chef-partner Anthony Calleo and Cherry Pie Hospitality (State Fare, Lee’s Chicken and Donuts), found itself on the receiving end of a modern phenomenon this weekend when guns rights activists bombarded its Facebook, Yelp, and Google pages with one-star reviews over the restaurant’s decision to ban concealed carry from its premises.

The issue began Friday afternoon with a one-star review by Facebook user Kyle Kelly. In his review, Kelly makes it clear that he won’t spend money at any business that prohibits concealed carry, and that’s what upset Cherry Pie Hospitality partner Lee Ellis.

“The thing about the review that got me worked up is that it wasn’t a review,” Ellis tells CultureMap. “The guy came by, saw the sign and wasn’t going to come in and give us money, because he couldn’t protect his family. It was all about the sign. It wasn’t about the pizza. It wasn’t about the service. It was not a legitimate review. Basically, I went in and called him out and said ‘FO.’”

While “FO” could stand for many things, many commenters on the review interpreted it to mean “fuck off.” When Kelly shared a screen shot of the reply with the Texas3006.com Facebook page, a group devoted to promoting concealed carry, the response was immediate. Negative reviews poured in from gun rights advocates and people who were upset that a business would engage its customers that way.

As the negative reviews mounted, Calleo posted to his personal page to ask Pi supporters to respond with five star reviews.

“The fact of the matter is, our rating on Facebook affects business here. It’s something I have to accept and acknowledge,” Calleo says. “That makes me want to say, ‘Hey, friends, this is what’s going on. If you can help us out please, we’re getting bombarded here a little bit.’ The response I got was superbly overwhelming and kind of humbling.”

According to Ellis, by Saturday night, Pi had jumped from 38 total reviews (mostly five star) to over 1,600: including 964 five-star reviews and 642 one-star reviews. Many of the one-star reviews were from outside the Houston-area, which means it’s unlikely they’d dined at the restaurant; instead, they were written by people who support concealed carry and were angered by a business that would tell a potential customer to “FO.”

Ultimately, the negative reaction turned personal. At least one Facebook page attempted to look up Calleo’s home address using his driver’s license information. At that point, Pi Pizza took down the review section of its Facebook page and began deleting posts. Ellis says they’re working with Facebook and Yelp to get the pages cleaned up.

One of the Facebook pages considers that a victory for their campaign.

Ellis says he won’t apologize to Kelly or remove the sign. He doesn’t think restaurants that serve alcohol should allow guns in the building and notes that many restaurants across the city share his opinion.

While many of the gun rights supporters are predicting their boycott will drive the restaurant out of business, Pi Pizza has benefited from the exposure. The restaurant had a line out the door both Saturday and Sunday, and that’s translating to sales.

“Our day was up 18-percent over last Saturday and 40-percent over last Sunday,” Ellis says.

Pi Pizza has created a FO Pizza and will donate 100-percent of proceeds to The 100 Club.