"Who will bell the cat?" joke

At a public meeting Khrushchev, the former Soviet leader, was denouncing Stalin. Somebody from the audience shouted:' As one of his colleagues at the time, why didn't you stop him?'
There was deathly stillness. Khrushchev thundered,' Who said that?' There was no response. After a long and petrified silence, Khrushchev replied to his question himself,' Now you know why'