Jackman, who turned 51 over the weekend, has been publicly sparring with Deadpool star Reynolds, 42, for years. The pair’s latest jokey “spat” was sparked when Jackman, performing on stage in his current musical world tour, quipped after one particularly energetic musical number: “Let’s see Ryan Reynolds do that.”

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“Don’t post that! Do not post that,” he told the cheering audience. “I’ll have three million tweets from him in the next 10 seconds.”

Three million tweets — or one very salty birthday message.

“Hello Hugh. I was just going to wish you Happy Birthday … then I saw what you said. In a word, hurtful. Enjoy the show, Hugh Jackman,” a party-hatted Reynolds said in the video message.

Reynolds then belted out a few lines of Happy Birthday to Jackman. “And I’m not even professionally trained, Jackman, you piece of sh*t!” he said before flipping the bird at the camera.

The pair’s jokey “feud” has been brewing online over the past couple of years as they play up to their respective fan bases. Memorable moments include Jackman filming an unflattering ad for Reynolds’ brand of gin, asking viewers to urinate on Reynolds’ Hollywood Walk of Fame star, and Reynolds quipping “Pretty sure those are protesters” under a picture of Jackman posing with fans.

Last November, Reynolds even went to the trouble of releasing a mock political ad to slam his rival.

“Hugh speaks with a charming accent, but he’s actually from Milwaukee,” Reynolds said in the ad, claiming Jackman is an impostor whose real name is “Hugh Michael Jackman”.

The pair have even enlisted other actors to their rivalry — Jake Gyllenhaal and John Krasinski among them.