Donald Trump to Jimmy Kimmel: My Past Pro-Clinton Comments Were 'a Little Bit' Insincere The presumptive GOP nominee admitted he once called her "wonderful."

 -- During an appearance on "Jimmy Kimmel Live!" Wednesday night, Donald Trump admitted that he wasn't sincere when he made glowing comments about Bill and Hillary Clinton prior to his bid for the presidency.

Kimmel asked the presumptive Republican presidential nominee about his once-effusive take on the Clintons, and Trump took the bait, acknowledging his past kind words. "She’s wonderful, the husband, everybody’s wonderful including contributions."

Kimmel interjected and asked, "So you were full of s***?”

Trump's response? "A little bit," he said, laughing.

And while Trump has labeled many of his foes with nicknames during his campaign, he said he won't be anointing Bill Clinton with a nickname. "I don’t want to do anything like that," he said. "I have come up with 'Crooked Hillary,' and you know what’s going on, she’s very crooked."

As for Bernie Sanders, Trump said he would welcome a debate with the Vermont senator. "If I debated him we would have such high ratings,” Trump told Kimmel. "If he paid a sum to charity I would love to do that." He said he "enjoys watching" Sanders duke it out with Clinton. "It's getting nasty. I had no idea it was gonna be so nasty."

Sanders took to Twitter after the show aired on the East Coast, writing, "Game on. I look forward to debating Donald Trump in California before the June 7 primary."

And when asked about the Washington Post investigation which speculated that Trump secretly posed as his publicist during a phone conversation using the alias "John Miller," he said, "It didn’t sound like me."

He added, "I’ve used aliases. I would use Barron,” a reference to his 10-year-old son with wife Melania. "I made a very good deal using that name."

During his opening monologue, Kimmel poked fun at Trump's suggestion to build a wall along the U.S.-Mexico border. “Tonight, those of you watching at home will have the rare opportunity to see Donald Trump on television," Kimmel said. "Trump is here in Hollywood, and I thought this was interesting, he has promised to make Hollywood Boulevard great again, by building a wall around Bill Cosby’s star on the Walk of Fame. And Guillermo is gonna pay for it!”