As the ceremony reached midway, Kimmel came on stage, fiddling with his phone.
"It has been more than two hours to the show and he has not tweeted yet, I am worried," he said referring to Trump's habit of tweeting.
There was a collecive gasp and laughter when Kimmel asked the production team to cast his phone's screen up for everyone to see what he was doing.
To everyone's shock, he posted "Hey, @realDonaldTrump u up."
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Trump had infamously called Streep an "overrated" actress after she had cricised the President's policies.
That was not his only salvo against Trump as he had earlier mocked him in his opening monologue
"This is being watched live by millions of people in 225 countries that now hate us," Kimmel said, adding, "I want to say thank you to President Trump. Remember last year when it seemed like the Oscars were racist?... It's gone thanks to him."
Kimmel also joked about "mediocre" and "overrated" Meryl Streep and noted that actors will give speeches that "the president will tweet about in all caps during his 5 a.M. Bowel movement tomorrow."