He gave them some ridiculous explanation, and they fell for it 'hook, line and sinker'. [=they believed his explanation completely]
(..) A watch ofgold with a diamondchain Hi diddle dee day An actor's life isgay lt'sgreat to be a celebrity An actor's life forme And the dummy fell for it... hook, line and sinker! And he still thinks we're his friends. And did Stromboli pay... plenty! That shows you how low HonestJohn will stoop, (..)1940 Pinocchio