When Ellen DeGeneres sat down with co-anchor Juju Chang of "Nightline" and was asked about presumptive Republican nominee Donald Trump, the talk show host did not hold back.

DeGeneres, ever respectful, said that Trump is welcome on her show. "I don't think he'd do the show, but I would have him on," she said.

"He's a bully."

When asked, "What does [Trump] represent to you?" DeGeneres doesn't hesitate.

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"He's a bully," she says calmly.

She then highlights one of Trump's favorite arguments.

Nightline/Facebook - facebook.com

DeGeneres points out that makes Trump such a bully is his willingness to play the "they started it" card. "You don't have to attack back," DeGeneres advises.

"With all due respect, 'He started it!' is the argument of a five-year-old."

Anderson Cooper has also pointed out this flaw in Trump's reasoning to Trump himself.

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In a CNN Town Hall, Cooper grilled Trump on why he retweeted the sexist meme depicting Heidi Cruz, the wife of Trump's former opponent Ted Cruz.

Trump's answer for sharing the meme was, "Look. I didn’t start it" to which Cooper had the perfect response: "Sir, with all due respect, that's the argument of a five-year-old."

Not doing himself any favors, Trump replied, "It is not. It is not!"

"The argument of a five-year-old is, 'He started it'!" Cooper reasoned.

Trump has also used the "they started it" argument during his online spats.

Trump loves to fight — especially on Twitter.

You can see clear proof of Trump's inability to let things go if you look at his Twitter feed. The Hollywood Reporter compiled a list of 20 of the best Trump twitter fights — published in 2013, long before Trump was running for office. He's only gotten worse.

His other favorite kindergarten-like tactic is to assign nicknames to his opponents. He's got "Goofy Elizabeth Warren," "Lyin' Ted Cruz," "Little Marco Rubio," "Crooked Hillary," and "Crazy Bernie Sanders."

DeGeneres really wasn't far off when she called Trump a bully, and Cooper wasn't off when he called Trump a five-year-old: the nominee proves it almost every day with juvenile statements and tweets. In fact, DeGeneres should probably expect an angry tweet from Trump soon.

You can watch the full clip of the Nightline interview with Ellen DeGeneres below.