As a young man, Richard Feynman was fascinated by the sounds of Italian, and faked Italian sounding gibberish, even to the point of "performing" it in front of his sister's Girl Scout troop.
Even McNulty on The Wire? When I saw him later on some talk show and he was speaking and holding himself as a posh Brit (ie himself) it almost broke my brain. So, yeah, he fooled me.
http://www.bookrags.com/studyguide-surely-youre-joking-mr-fe...