What did Valli see on her way that made her laugh?

Valli saw a young cow, whose tail was high in the air, running right in front of the bus in the middle of the road. The bus slowed and the driver sounded his horn loudly. However, the more he honked, the more frightened the cow became and it kept running faster and faster, right in front of the bus. Valli found it so amusing that she had tears in her eyes. At last, the cow moved off the road.