Stephen Colbert was left puzzled on Wednesday night by Donald Trump’s verbal attack on New Hampshire Gov. Chris Sununu, who endorsed Nikki Haley for the GOP presidential nomination.

“This guy, he’s gotta be on something, I’ve never seen anybody with energy,” Trump said of Sununu earlier this week. “He’s like, uh, hopscotch.”

The insult left Colbert puzzled. 

“He really is losing it,” Colbert fired back at Trump, who has faced increased scrutiny over his recent gaffes and stumbles. “That sentence makes absolutely no hopscotch.”

See more in the Wednesday night “Late Show” monologue: