Prince Harry Warns Barack Obama ... Don't Make Me Give You 'the Face'

12/17/2017 7:28 AM PST

Prince Harry Interviews Barack Obama for the BBC

When Harry Met Barry ... Harry had to lay down the rules.

Prince Harry interviewed Prez Obama for BBC Radio 4's "Today" and before they got started ... Barack openly mocked himself for being a slow ... painstakingly ... deliberate speaker. He offered to use a British accent, if it would help -- and Harry threatened to give him "the face." Watch, you'll get it.

You can tell the Prince was very nervous -- he conducted the interview as part of a guest editorship with the BBC.

Obama found a way to calm him down though ...by offering to turn the tables.