A "bullshiner" is a cleaner version of "bullshitter". It waqs made mainstream by favourite Big Brother housemate, Mario Marconi.
The word is often part of the expression "Billy Bullshiner", There are many theories as to why Mario puts the word/Name "Billy" at the begging, one theory is that, because it's alliteration it makes it sound good and rolls of the tongue. Another is that the name "Billy" often crops up before other famous derogatory slurs, such as "Billy no Mates".
Mario Marconi ain't no Billy Bullshiner, I can tell you that!