President Trump is “Mad” at Democratic presidential candidate Pete Buttigieg.

“Alfred E. Neuman cannot become president of the United States,” Trump told Politico on Friday, using the name for the gap-toothed, big-eared Mad magazine mascot to refer to Buttigieg.

But the 37-year-old mayor of South Bend, Ind., had a millennial pause before he could respond to the diss.

“I’ll be honest. I had to Google that,” Buttigieg said. “I guess it’s just a generational thing. I didn’t get the reference.”

Trump has unveiled a new batch of nicknames for the 2020 campaign.

On Friday, he tweeted, “Looks to me like it’s going to be SleepyCreepy Joe over Crazy Bernie. Everyone else is fading fast!”

Ex-Vice President Joe Biden and Vermont Sen. Bernie Sanders are considered the Democratic front-runners.