Completely and obviously false, fake, or illegitimate; not genuine or authentic in the slightest. (There has never been a three-dollar bill in circulation in the United States.) Primarily heard in US. The guy said he was selling Rolexes, but this thing is phonier than a three-dollar bill. The senator's hammed-up, teary-eyed speech was phonier than a three-dollar bill, if you ask me.