NBC’s Tonight Show host Jimmy Fallon responded on air Monday night to a Trump tweet, asking his audience: “shouldn’t he have more important things to do?”

Flashback: Trump's tweet — saying Fallon was "whimpering to all that he did the famous "hair show"" and calling for Fallon to "be a man" — came after Fallon expressed regret for messing with Trump's hair in a September 2016 interview on his show.

Trump once again brought up Fallon — as well as some other late night hosts — at a rally in South Carolina Monday night where he called Fallon a "lost soul" and "a poor guy, because now he's going to lose all of us."

Fallon's response:

• “When I saw that Trump insulted me on Twitter, I was going to tweet back immediately, but I thought, ‘I have more important things to do.’ Then I thought, ‘Wait, shouldn’t he have more important things to do? He’s the president of the United States.’ What are you doing! You’re the president! Why are you tweeting at me?”
• “As you may have heard, last night the president of the United States went after me on Twitter. So Melania, if you’re watching, I don’t think your anti-bullying campaign is working.”
• “The president went after me on Twitter: That’s pretty much the only thing I have in common with NFL players.”

Fallon also made a donation to the Refugee and Immigrant Center for Education and Legal Services in honor of the president's tweet.