Rihanna called out Snapchat for running a sickening ad that asked users if they “would rather slap Rihanna or punch Chris Brown” — and sent the stock of the app’s parent company tumbling as much as 5 percent.

“Now SNAPCHAT I know you already know you ain’t my fav app out there!” the “Work” singer wrote in an Instagram tirade on Thursday. “I’d love to call this ignorance, but I know you ain’t that dumb!”

The shocking ad — which referred to Brown’s 2009 conviction for brutally assaulting Rihanna in a car — provoked disgust on social media over the weekend, with some vowing to delete Snapchat from their phones.

“This isn’t about my personal feelings, cause I don’t have much of them … but all the women, children, and men that have been victims of DV in the past and especially the ones who haven’t made it out yet … you let us down! Shame on you. Throw the whole app-oligy away.”

Even Chelsea Clinton weighed in on the mess, tweeting this week that it was “Awful that any company would approve this.”

Snapchat’s parent, Snap Inc., responded Thursday by calling the ad “disgusting” and saying it “never should have appeared on our service.”

Earlier in the week, Snapchat had given a relatively clinical statement that the offending ad “was reviewed and approved in error as it violates our advertising guidelines.”

The Thursday fracas sent Snap shares down 5 percent, to $16.91 by early afternoon — their lowest levels this month. They recovered slightly to close at $17.20, down 3.6 percent.

In an infamous picture taken after the assault, Rihanna, who was then 22, was seen with a black eye, bloody lips, and cuts on her forehead — all at the hands of her then-boyfriend Brown.

In 2009, Brown pleaded guilty to the assault and paid a fine and did community service.

The selloff in Snap shares is the second at the hands of a celebrity in less than a month. In February, Kylie Jenner complained about the texting app’s redesign, causing the company to lose more than $1 billion in market value.