250
Śrīmad-Bhāgavatam
[Canto 10, Ch. 11]
TRANSLATION
Sometimes Kṛṣṇa and Balarāma would play on Their flutes, sometimes They would throw ropes and stones devised for getting fruits from the trees, sometimes They would throw only stones, and sometimes, Their ankle bells tinkling, They would play football with fruits like bael and āmalakī. Sometimes They would cover Themselves with blankets and imitate cows and bulls and fight with one another, roaring loudly, and sometimes They would imitate the voices of the animals. In this way They enjoyed sporting, exactly like two ordinary human children.
PURPORT
Vṛndāvana is full of peacocks.  Kūjat-kokila-haṁsa-sārasa-gaṇākīrṇe mayūrākule.  The Vṛndāvana forest is always full of cuckoos, ducks, swans, peacocks, cranes and also monkeys, bulls and cows. So Kṛṣṇa and Balarāma used to imitate the sounds of these animals and enjoy sporting.
TEXT 41
कदाचिद् यमुनातीरे वत्सांश्चारयतोः स्वकैः ।
वयस्यैः कृष्णबलयोर्जिधांसुदैत्य आगमत् ॥४१॥
kadācid yamunā-tīre vatsāṁś cārayatoḥ svakaiḥ vayasyaiḥ kṛṣṇa-balayor jighāṁsur daitya āgamat
kadācit —sometimes;  yamunā-tīre —on the bank of the Yamunā;  vatsān —the calves;  cārayatoḥ —when They were tending;  svakaiḥ —Their own;  vayasyaiḥ —with other playmates;  kṛṣṇa-balayoḥ —both Kṛṣṇa and Balarāma;  jighāṁsuḥ —desiring to kill Them;  daityaḥ —another demon;  āgamat —reached there.
TRANSLATION
One day while Rāma and Kṛṣṇa, along with Their playmates, were tending the calves on the bank of the River Yamunā, another demon arrived there, desiring to kill Them.