How Ganesha Kills demon Gajamugasuran?

Pastimes of Ganesh Chaturthi no. 9

Once there was demon called Gajamugasuran. He done deep penance and worshiped Lord Shiva, who granted many boons to him by which he became extremely powerful. He put to Devas and Rishis into great distress. He forced devas to do 1008 Thoeppukaranams in the morning, afternoon and also in the evening.

Thoeppukaranam means to sit down and then stand up holding one's ears with hands crossed, that is his left ear with his right hand and right ear with left hand.

The Devas prayed to Lord Shiva to rescue them from this evil demon. Than Ganesha was sent by lord shiva to overcome Gajamugasuran. Ganesha went with several weapons like arrows, bow, sword, axe, etc. However since Gajamugasuran had been granted the benefit of not being destroyed by all of this weapons, none of the weapons worked effective for Lord Ganesha.

Ganesha than broke his own right tusk and used it to kill Gajamugasuran. Gajamuga rushed to Ganesha as a small mouse i.e. a mooshikam. Ganesha crushed ego and vanity of Gajamugasuran and sat on the him. The humbled Gajamugasuran bowed before Ganesha, which was then Ganesha accepted as the mooshikam "Vahana".

Lord Ganesha can be Pleased by doing "Thoepukaranam" by his devotees when they commit anything wrong.