Donald Trump Claims He Took Helicopter Ride With Kamala's Ex, He Calls BS

Donald Trump's got a future career as a fantasy writer ... so says the former mayor of San Francisco, who's calling Trump's tale about the two of them a piece of "creative fiction."

Here's the deal ... during Trump's news conference with reporters at Mar-A-Lago Thursday, he pulled out all his usual moves -- making controversial claims and name-dropping some big-time public figures.

One of those figures was ex-Mayor of S.F. Willie Brown, who happens to have once dated DJT's presidential opponent Kamala Harris -- and who Trump says he once flew with in a helicopter that nearly crashed.

Check out the clip -- Trump claims he knows Willie super well -- and, says they almost died during a shaky landing ... one Donald says really freaked out Brown.

He adds WB told him terrible things about Kamala, though Trump doesn't go into great detail ... and, according to Willie, he didn't go into detail 'cause it's all BS.

Brown spoke with local San Fran outlet KRON 4, saying he's never conducted business with or taken a helicopter ride alongside Trump. Willie says this is all some "creative fiction" Donald's cooking up to disparage Kamala.

He adds he wouldn't get into a helicopter with Donald either ... fearing someone with an agenda might tamper with the aircraft and kill them both.

It's possible Trump's trying to get people talking about Kamala's political origins again ... remember, some conservatives have either implied -- or straight-up claimed -- she slept her way to the top -- including a guest on Fox Business who called her the "original Hawk Tuah Girl."