President Donald Trump's niece Mary not only spent her life around the president and his family, but she also has the benefit of being a psychologist who could legitimately assess the life and mental health of her uncle.

Speaking to MSNBC's Lawrence O'Donnell, she explained that in one particular moment in the Tuesday evening debate, Trump seemed triggered by former Vice President Joe Biden's use of the phrase "not smart" in reference to a policy. Trump went off.

"Did you use the word 'smart?'" Trump asked after Biden insulted Trump's coronavirus plan as not being "smart."

"So you said you went to Delaware State but you forgot the name of your college," Trump continued, falsely claiming something Biden never said. "You didn't go to Delaware state. You graduated either the lowest or almost the lowest in your class. Don't ever use the word 'smart' with me. Don't ever use that word."