For U.S. President Donald Trump’s 73rd birthday, Twitter users across the world offered him a one-of-a-kind gift – but he probably won’t like it.

On Friday, the hashtag #JohnMcCainDay soared to the top of Twitter’s trending list in Canada and the U.S.

Trump regularly airs his dislike for the late Republican senator, who repeatedly broke from the Trump administration in several key areas. He infuriated Trump after he sided with Democrats and killed Republican attempts to repeal President Barack Obama's health care law.

Last month, the White House ordered the Navy to keep the USS John S. McCain, a warship rededicated in McCain’s honour, out of sight during Trump's visit to Japan. Trump denied any involvement in the order, but reiterated to reporters at the time that he "was not a big fan" of McCain.

Even as a candidate, Trump slagged the American war hero’s time as a prisoner of war in Vietnam, saying he preferred “people who weren’t captured.”

The idea to make #JohnMcCainDay go viral on Trump’s birthday started with Andy Lassner, the executive producer of “The Ellen DeGeneres Show.” Lassner tweeted a callout Friday morning.

“Honoring an American hero today. Let’s celebrate @realDonaldTrump’s birthday today by having #JohnMcCainDay trend. I’m sure this would mean a lot to a patriot like Donald Trump,” tweeted Lassner, who often criticizes the Trump administration.

The hashtag quickly became one of the widely-shared tweets of the day. Members of Congress, including Democrat Marc Veasey from Texas and Joyce Beatty from Ohio, joined in to troll the president with inspiring quotes from McCain.

McCain died last December after battling brain cancer. But his death didn’t do much to tamp down Trump’s criticism. In March, Trump tweeted that McCain was “last in his class” at the U.S. Naval Academy. McCain’s daughter, Meghan McCain, responded by slamming Trump’s life as “pathetic” and saying he will “never be a great man.”

On Friday, Meghan McCain reacted to #JohnMcCainDay by retweeting Lassner’s original callout with two emojis: a heart and an American flag.