Donald Trump called Pete Buttigieg 'Alfred E. Neuman.' The millennial mayor had to Google it.

The 2020 presidential race surely has turned mad. 

President Donald Trump took another shot at Pete Buttigieg on Friday, comparing the young mayor of South Bend to the longtime mascot of Mad Magazine, a freckled-faced cartoon boy.

"Alfred E. Neuman cannot become president of the United States,” the president told Politico.

The shot landed home with baby boomers and Gen Xers, many of whom remember thumbing through the iconic satirical magazine. Buttigieg, perhaps like many millennials, seemed puzzled, though to be fair, a Mad-based sketch comedy TV show ran for 15 years starting in 1995.

"I’ll be honest. I had to Google that," he told Politico. "I guess it’s just a generational thing. I didn’t get the reference. It's kind of funny, I guess. But he’s also the president of the United States, and I’m surprised he’s not spending more time trying to salvage this China deal." 

Buttigieg was referring to negotiations to end a year-and-a-half-old trade war between the world’s two largest economic powers.

His response to Trump, however, prompted a reaction from Mad Magazine — still in print, according to its Twitter profile.

"Who’s Pete Buttigieg?" the magazine said in one of several tweets aimed at the 37-year-old candidate. "Must be a generational thing."

Mad wasn't finished there, though. Another tweet aimed at the famously multilingual candidate includes Neuman's signature phrase "What — me worry?" — in Norwegian.

No word on whether the mayor has read it, in Norwegian or otherwise. 

Trump, though, clearly is thinking about Buttigieg. His comment Friday comes on the heels of a remark he made at a Wednesday campaign rally. 

"Boot-edge-edge," the president sounded out, according to a story reported by The Hill, "They say 'edge-edge.'"

Trump continued, apparently thinking little of Buttigieg's stature on the world stage: "He’s got a great chance. He’ll be great. He’ll be great representing us against President Xi (Jinping) of China. That’ll be great."

Trump alluded to Buttigieg on a conservative radio show last month as he speculated which Democrat he might face in the 2020 election, saying "It could be the mayor from Indiana."

Call IndyStar reporter Chris Sikich at 317-444-6036. Follow him on Twitter: @ChrisSikich.