President Donald Trump dismissed the youngest candidate in the Democratic field by comparing him to a caricature created decades before Pete Buttigieg was even born.

"Alfred E. Neuman cannot become president of the United States," Trump said when asked by Politico what he thought of Buttigieg, the 37-year-old mayor of South Bend, Indiana. The reference to the gaptoothed, big-eared boy made famous as a mascot for Mad magazine did just as much to show Trump's age as Buttigieg's.

The magazine used the illustration on its cover back in 1956 as a write-in candidate for president. While fairly ubiquitous in pop culture, the popularity of the cartoon and the magazine peaked in the 1970s.

Buttigieg, asked about the president's swipe, admitted to not knowing the reference and trolled the president right back.

"I'll be honest. I had to Google that," Buttigieg told reporters Friday. "I guess it's just a generational thing. I didn't get the reference. It's kind of funny, I guess."

Mad magazine, whose Twitter bio is: "STILL IN PRINT," in return trolled Buttigieg for not knowing the cartoon. "Who's Pete Buttigieg? Must be a generational thing," the magazine tweeted early Saturday morning.

The millennial mayor plays up his youth as an asset. He's fond of saying it will be 2054 when he's the same age as Trump, making him part of the generation that has the greatest long-term stake in the political decisions made today.

Trump's use of nicknames for his political opponents is part of his overall political strategy to put them in boxes of his own design. Once he pegged former Florida governor Jeb Bush, R, as "Low Energy," Sen. Marco Rubio, R-Fla., as "Little Marco" and 2016 presidential opponent Hillary Clinton as "Crooked Hillary," the names stuck. He's already started in on his potential 2020 challengers, calling Sen. Bernie Sanders, I-Vt. "Crazy Bernie" and more recently updating his moniker for former vice president Joe Biden from "Sleepy Joe" to "Sleepy Creepy Joe."

The Alfred E. Neuman crack is Trump's attempt to reduce Buttigieg to a goofy caricature.

Buttigieg shrugged off the president's insult. "I'm surprised he's not spending more time trying to salvage this China deal," the mayor said, referring to stalled trade talks between the U.S. and China.

While Buttigieg trails Biden and Sanders, he has placed as high as third in some national polls, so he's on Trump's radar. While Trump has focused most of his attention on Biden, he took a few shots at Buttigieg at a recent rally, mocking the idea of the young mayor sitting down with Chinese President Xi Jinping.

"That'll be great. I want to be in that room, I wanna watch the one," Trump said.

Asked about Trump singling him out on Wednesday, Buttigieg told reporters, "You can't get too worried about the name-calling and the games he plays.

"I was thinking of the Chinese proverb that goes, ‘When the wind changes, some people build walls and some people build windmills.’ "