The Democratic presidential candidate told Bill Maher on "Real Time" Friday night that he'd have "loved" to discuss policy issues with the real estate mogul.
"Mr. Macho chickened out," said Maher, prompting Sanders to challenge the presumptive GOP presidential nominee once again.
"Trump claims to be a real tough guy, pushes people around," Sanders said. "Hey Donald, come on up, let's have a debate about the future of America."
Maher's interview with Sanders covered multiple issues, including some people's perception that he's a hardcore socialist -- which he insisted he isn't.
But it soon circled back to Trump, who Sanders said was difficult to strategize against because of his lies and apparent unaccountability.
"I have a lot of Republican colleagues and friends who I disagree with," Sanders said. "They're not crazy. They're honest people."
Sanders called Trump "a pathological liar." "I don't mean to be malicious, but it's just the damn truth," he added. "He would not only be an embarrassment, but a real danger to this entire world if he were to become president."
Check the interview out in the clip above.
Also on the show, Maher called on people to continue using the #WhinyLittleBitch hashtag when talking about Trump on social media -- in order to brand him "like he brands everybody else." The #ChickenTrump hashtag also surfaced on the show's Twitter account.
Watch that clip here: