Ganesha was very fond of sweets. There was one that he especially adored, a dumpling called a modaka, which has a steamed wrapping made of rice flour and a filling that absolutely bursts with coconut and dried fruit. Whenever Ganesha saw a dish of modakas, he had to stop and eat one. Of course, once he had eaten one, he had to eat another. Then another, and another, until the dish, in no time at all, was empty.
Once it so happened that the people on earth were preparing for a special feast. In a village house, someone had set out an enormous platter of modakas to cool. "Aha!" cried Ganesha, when the aroma reached him, his trunk twitching in delight. He hurried to the thatched house, and slipped in unobserved through the back-door. Making himself comfortable he then began to help himself with the modakas.
Soon even his tremendous belly was filled. Ganesha looked at the platter. "There are still some left," he remarked in surprise. He picked up the last few modakas and stuffed them into his mouth.
"That was good," he said, climbing on to the mouse's back. "Let us go." The mouse started up obediently.
At that very moment a snake slithered across the threshold. The mouse startled, tripped, and his master went flying off his back.
Alas, Ganesha's great stomach was like a sack that is too full and can hold no more. When his body hit the ground, his stomach burst, spilling modakas in every direction.
"Oh master, forgive me," said the mouse. "You are hurt."
"Shhh," said Ganesha, reaching out for the spilled modakas and hurriedly trying to put them back into his stomach. "No one saw this happen."
Looking around for something to hold his belly together, he saw the snake, still in the doorway.
"The very thing," said Ganesha, and he picked up the snake and tied it around his waist like a belt, to hold in the modakas and keep his belly closed.
He still wears the snake around his middle.
This description by Nitin Kumar, Executive Editor, Exotic India.
Krishnaswami, Uma. The Broken Tusk, Stories of the Hindu God Ganesha: Calcutta, Rupa & Co, 1997.