The official Twitter account for Arby's trolled Trump GOP primary challenger Mark Sanford Mark SanfordOn The Money: Business world braces for blue sweep | Federal Reserve chief to outline plans for inflation, economy | Meadows 'not optimistic' about stalemate on coronavirus deal Trump critic Sanford forms anti-debt advocacy group Republicans officially renominate Trump for president MORE on Wednesday following his appearance outside one of its restaurants on the campaign trail in Iowa.

Sanford, the former governor of South Carolina, appeared to invoke a slogan for rival fast-food restaurant Wendy's when he went after President Trump Donald John TrumpFederal prosecutor speaks out, says Barr 'has brought shame' on Justice Dept. Former Pence aide: White House staffers discussed Trump refusing to leave office Progressive group buys domain name of Trump's No. 1 Supreme Court pick MORE outside the Arby's, asking the administration, "Where's the beef?"

“Sir, this is an Arby’s," the fast-food chain tweeted in response to a clip of Sanford's remarks.

Sir, this is an Arby's. — Arby's (@Arbys) September 25, 2019

The 2020 rival had held a sandwich outside the Arby's in Iowa as he criticized the Trump administration for not completing the border wall between the U.S. and Mexico.

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“Where’s the beef on that promise, because your wall has not been built over the course of the administration’s last couple years,” Sanford said, according to a video tweeted by a Des Moines Register reporter.

It's unclear if Sanford was aware that the phrase he used — "Where's the beef?" — was associated with Wendy's.

The slogan was used in commercials for Wendy’s in the 1980s, and presidential candidate Walter Mondale famously invoked the slogan to criticize Sen. Gary Hart during the 1984 Democratic primary.

Arby's tweet Wednesday alluded to another popular joke on Twitter — “Sir, this is a Wendy’s” — which is sometimes used to mock aggressive tweets from social media users.

Sanford announced earlier this month that he would launch a challenge against Trump for the 2020 GOP nomination, saying he hopes to improve “the ideas that the Republican Party stands for.”