another way of saying that any information recieved from a certain source can't be taken seriously because that source has been wrong before, or lacks credibility.
"hey did you hear Elvis is still alive?? he was seen at a casino in vegas last week! actually they say he's even the owner!!"
Short-hand for the word floccinaucinihilipilification, meaning the estimation of something as valueless (encountered mainly as an example of one of the longest words in the English language).