Once Balarama and other friends came to Krishna's mother, yashoda and complained to her that "Krishna eats clay while we are playing."  the angry Yashoda immediately called Krishna and asked him whether it was rightly complained. 

However,Krishna denied telling her that the friends were lying so that harass me and get shouting from mother. But, Yashoda was not convinced and insisted that he should open his mouth and show. Immediately, Krishna opened his mouth and Yashoda had a look inside his mouth. 

To her surpsrise she saw the whole Universe, 'Vishwa', like sun, moon, planets, oceans, mountains etc.,and she also saw herself with krishna drinking milk on her lap.  She thought she was dreaming but soon she came to know the truth and she embraced krishna and loved him.