Vishnu's Dharma Chakra

When lord Ganesha,
the god of everlasting wisdom was a small boy
He used to play in all the free locals.
When he was playing in vaikundam,
the aboard of lord vishnu,
young ganesha was very much attracted by Lord Vishnu's Dharma Chakkara.
Lord Vishnu was in deep meditation.
Ganesha thought that the chakkara to be a toy and wanted to play with it.
Suddenly ganesha grabbed the chakkara from Lord Vinshu's hands.
On realizing that the Dharma Chakkara was missing from his hand.
Lord Vishnu was deeply troubled.
Lord Vishnu requested several times to ganesha to return it to him,
But Ganesha on fear of losing the chakkara put it inside his mouth.
Hmmmm.......What can be done?
How to get back the Dharma Chakkara from Ganesha?
What else can I do?
MMMMMM......There is only 1 way to get back the chakkara
Let me try out this and try to make him laugh
That is the only way
MMMMMMMM
Lord Vishnu did not know how to get it back from Ganesha
He thought of making Ganesha laugh.
So he caught hold of his own ears with his hands,
then he bent down and straightened up many times
performing the Thoppu Karanam
On seeing this Ganesha began to laugh
He shaked so much with laughter that the chakkara,
fell out of his mouth.
immediately the chakkara reached the hands of lord Vishnu.
Lord Vishnu performed the Thoppu Karanam infront of Ganesha,
and obtained his favor.
That is why we need to offer thoppu karanam,
to please Lord Ganesha,
and obtain his blessings to get our favors fulfilled.