An oxymoron that described a piece of information, theory or idea that despite being repeated frequently, quoted in the media, and known to practically everyone you ask in the street, is still false or misleading. Often used to describe theories in popular science that may have little or no valid evidence to back them up ( A fact that has not been proved is like a virgin who has intercourse, so the phrase is contradictory.)
From the quote by Professor Hubert Farnsworth ( Character in Futurama ) describing an old wives tale
A sexual transmitted infection that is received from either sexual intercourse with someone that went to a school in the Bellefonte Area School District. This will lead to ‘loss of sense of style,’ ‘increased annoyingness,’ and ‘a crippling addiction to nicotine.’
“Matthew had sex with Julie, and I know that he got Bellefontism because he is now addicted to cigarettes and is really annoying!”
Meaning you are saying 100% truth. More powerful than just saying trust that or believe that. Sometimes said with anger. Coined by the living legend the hubba