Gai Jatra, the festival of cows, (Gai means cow and jatra means festival in Nepali) is celebrated in Nepal, mainly in Kathmandu valley by the Newar and Tharu community. The festival commemorates the death of people during the year. During the festival, cows are marched in the streets and generally celebrated in the Nepalese month of Bhadra (August–September). It falls on the 1st day of the dark fortnight of Gunla according to the lunar Nepal Era calendar. Peoples also distribute food to others. The festival of cows is one of the most popular festivals of Nepal.
However, the modern form of celebration of Gai Jatra came into existence in the medieval period of Nepal during the reign of Malla Kings. The present form of Gai Jatra with humorous acts, parody, comedy and was started by then King of Kathmandu Pratap Malla. He made Rani Pokhari (Pond) in the heart of Kathmandu and build a temple in the middle of the same pond in for the queen the memory of the beloved son of them.
Traditionally every family who had death in the family during the preceding year must participate in a procession through the streets of Kathmandu leading a cow.
If a cow is unavailable then a young kids dressed as cow is considered a fair substitute. However, there started tradition of leading a cow with kids in funny costumes.