Washington (CNN) No one -- probably not even Donald Trump -- expected former FBI Director James Comey's memoir about his life and times with the President who fired him was going to be a fun read for the man who calls 1600 Pennsylvania Avenue home.

But if the early reports of Comey's "A Higher Loyalty" are any indication, the fired FBI director decided to take on Trump with both barrels -- delivering an absolutely unsparing and embarrassing portrait of the most powerful person in the country.

In an excerpt of the book obtained by the New York Post , Comey recounts that at a dinner with Trump early in his presidency, the conversation turned to the possible existence of a salacious tape involving the president of the United States and urination.

Writes Comey, according to the Post:

"He brought up what he called the 'golden showers thing. It bothered him if there was 'even a one percent chance' his wife, Melania, thought it was true. ... He just rolled on, unprompted, explaining why it couldn't possibly be true, ending by saying he was thinking of asking me to investigate the allegation to prove it was a lie. I said it was up to him."

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