Sen. Bernie Sanders (I., Vt.) mocked Hillary Clinton Thursday night on MSNBC after being questioned about a passage from Clinton's upcoming 2016 election memoir, What Happened, laughing at the notion that he stole her ideas.

Before Chris Hayes asked the question they both laughed, and Sanders said he was "shocked" that he would be asked about Clinton blaming him for her loss to Donald Trump in 2016.

"I'm shocked you're interested in this," Sanders said.

Hayes started reading the passage from Clinton's book where she complained that Sanders would come up with "loftier" and "leftier" policy proposals than Clinton's.

"Jake Sullivan, my top policy advisor, told me it reminded him of a scene from the 1998 movie There's Something About Mary. A deranged hitchhiker says he's come up with a brilliant plan. Instead of the famous ‘eight-minute abs' exercise routine he's going to market ‘seven-minute abs.' It's the same, just quicker," Hayes read.

"I.e. Bernie Sanders just stole all of Hillary Clinton's ideas. Does anybody really believe that?" Sanders said, snickering.

Sanders then said he helped bring forth "radical" ideas that have become part of the mainstream for the Democratic Party. To his point, Sens. Elizabeth Warren (D., Mass.) and Kamala Harris (D., Calif.) have signed onto his single-payer, "Medicare for all" health care proposal.

"The truth is and the real story is that the ideas that we brought fourth during that campaign, which were so crazy and so radical, have increasingly become mainstream," he said.