Covering one's own ear to steal the bell, foolish self cheating behaviour
At the time when Fan, a nobleman of the state of Jin, became a fugitive, a commoner found a bell and wanted to carry it off on his back. But the bell was too big for him. When he tried to knock it into pieces with a hammer there was a loud clanging sound. He was afraid that someone will hear the noise and take the bell from him, so he immediately stopped his own ears.
To worry about other people hearing the noise is understandable, but to worry about himself hearing the noise (as if stopping his own ears would prevent other people from hearing) is absurd.