So here is a version with what I believe to be the cor Definitions by the largest Idiom Dictionary. Fool me once, shame on you; fool me twice, shame on me phrase. Fool me twice, shame on me.” The phrase is so popular that almost everyone knows it without having to say the whole thing and the meaning of the entire phrase is implied by the short “fool me once” phrase. The phrase “fool me once” is a shortened version of a longer phrase. I did not agree with some of the chords in other tabs for this song on various sites, and the timing is always way off on them as well. Definition of Fool me once, shame on you; fool me twice, shame on me in the Idioms Dictionary. What does Fool me once, shame on you; fool me twice, shame on me expression mean? Fool me once, shame on you; fool me twice, shame on me - Idioms by The Free Dictionary. The long version of the phrase is “Fool me once, shame on you.