WATCH: Joe Biden is confused about whether he's had a cognitive test, suggests black anchor is a coked-up 'junkie'

On June 30, Joe Biden said that he had been tested for cognitive decline. Now he say he hasn't been during a recent interview with CBS News' Errol Barnett.

When Barnett questioned Biden on whether he had been tested for cognitive decline, Biden gave a bizarre response: "No I haven't taken a test. Why the hell would I take a test? C'mon man. That's like saying you, before you got in this program, if you take a test where you're taking cocaine or not, what do you think, huh? Are you a junkie?"

Barnett followed Biden's response up with asking the presidential candidate what he thought about President Donald Trump, who "brags about" his cognitive tests, saying that Biden's cognitive tests may present a problem for voters.

Biden responded: "If he [Trump] can't figure out the different between an elephant and a lion, I don't know what the hell he's talking about. Did you watch that—yeah, look, c'mon man, I know you're trying to goad me, but I mean, I'm so forward to looking to have an opportunity to sit with the president or stand with the president in debates. There's going to be plenty of time—and by the way, as I joke with him, I shouldn't say it... I'm gonna say something I probably shouldn't say. Anyway, I am, uh, I am very willing to let the American public judge my physical and mental fitness."

A questioner in Wilmington, Delaware brought up the point on June 30 that some have speculated that Biden may be "subject to some degree of cognitive decline," finally asking Biden himself if he had "been tested for some degree of cognitive decline."

Biden responded: "I've been tested and I'm constantly tested. Look, all you gotta do is watch me, and I can hardly wait to compare my cognitive capabilities to the cognitive capability of the man I'm running against."

The American people don't appear to be fooled, with 55 percent of the population believing that Biden shows some signs of dementia as of mid-June.

Biden also slipped into hot water back in late May when he suggested that black people "ain't black" if they don't vote for him in the presidential election during an interview on Charlemagne tha God's radio show, The Breakfast Club.