Here's why '100 percent' means nothing: Trump has long history of lying under oath
President Donald J. Trump arrives at the Memorial Amphitheater during the 149th annual Department of Defense (DoD) National Memorial Day Observance. (DoD Photo by U.S. Army Sgt. James K. McCann)

On Friday, President Donald Trump said that he is "100 percent" willing to testify under oath about his private conversations with fired FBI Director James Comey.

However, according to multiple sources who have been involved with litigation with Trump, the president has a history of lying under oath, so much so that his own bankruptcy lawyers would only meet with him in pairs in order to have a witness to every word that came out of his mouth.

In one sworn deposition from 2007, according to the Washington Post, Trump told 30 lies in two days.

During a lawsuit against author Tim O'Brien -- who publicly questioned Trump's "billionaire" status -- Trump "misstated sales at his condo buildings. Inflated the price of membership at one of his golf clubs. Overstated the depth of his past debts and the number of his employees," the Post's David Fahrenthold.

“Trump’s falsehoods were unstrategic — needless, highly specific, easy to disprove. When caught, Trump sometimes blamed others for the error or explained that the untrue thing really was true, in his mind, because he saw the situation more positively than others did," the Post said.

The experience, O'Brien said, taught him that Trump is "a routine and habitual fabulist," whether he's under oath or not.