The third line from the saying "Fool me once, shame on you; fool me twice, shame on me" is "fool me twice, shame on me."

You say "Fool me once, shame on you! Fool me twice, shame on me!"

This means, if you play a trick on me and I fall for it, shame on you for fooling me. But if you play a trick on me and I fall for it again, then shame on me for being foolish.

fool me once, shame on you. fool me twice, shame on me.

george bush

The full saying is "Fool me once, shame on you; fool me twice, shame on me." It means that being tricked or deceived once is the fault of the person who tricked you, but if you allow it to happen again, then you are also at fault for not learning from the mistake.