Call it the vulgarity bump.

Stephen Colbert’s controversial — and bleeped — quip on May 1 about “the only thing [Trump’s] mouth is good for” attracted an average 283,000 added viewers on each of the following days last week — powering the CBS show to its largest weekly margin of victory over its NBC late-night rival.

The ratings win for “The Late Show with Stephen Colbert” was its 14th straight — a feat powered by Colbert’s rabidly anti-Trump tone.

For the week ended May 5, Colbert drew an average of 3.06 million viewers — beating the 2.65 million average for “The Tonight Show Starring Jimmy Fallon” by 15 percent.

The 410,000-viewer edge for CBS was the largest over NBC since Colbert climbed into the host’s chair on Sept. 8, 2015.

To be sure, Colbert’s potty-mouthed Trump “c**kholster” tirade caught the attention of the Federal Communications Commission, which is investigating complaints about the language.

But there is no denying the foul-language helped draw a crowd.

In a radio interview last Thursday, FCC Chairman Ajit Pai said the agency would “take the appropriate action” should the talk-show host’s remarks be found obscene.

Few media experts expect the FCC to follow up, however, as broadcasts between 10 p.m. and 6 a.m. are granted leniency for indecent and profane content.

Jimmy Fallon, meanwhile, over at the Peacock Network, continued to win the 18-to-49 age group coveted by advertisers with a 0.6 rating — versus 0.5 for Colbert.