On this day, the great night of the Lord Shiva, devotees stay awake throughout the night offering prayers to Lord Shiva. They offer special food made from the fruits of the season, root vegetables and coconut to the Lord. Special celebrations are held in some of the major Shiva temples at Varanasi, Kalahasti (Andhra Pradesh) and Chidambaram (Tamil Nadu).
This is an important day for the devotees of Shiva, who stay awake throughout the night, praying to him. In all major centers of Shiva worship, Shivratri, also called Maha Shivratri, is a grand occasion. From the very early morning, Shiva temples are filled with devotees, mostly women, who come to perform the traditional worship of the Shivalinga.
All through the day, devotees abstain from eating food and break their fast only the next morning, after the nightlong worship. The day is considered especially auspicious for women. Married women pray for the well being of their husbands and sons, while unmarried women pray for a husband like Shiva, who is considered the ideal husband.
Hymns in praise of Lord Shiva are sung with great fervor and devotion. People repeat the Panchakshara mantra, Om Namah Shivaya. It is believed that one who utters the name of Shiva during Shivratri with proper devotion is freed from all sins. He reaches the abode of Shiva and lives happily there. He is liberated from the cycle of birth and death. Many pilgrims flock to the places where there are Shiva temples.
Shiva being an ascetic god, Maha Shivratri is very popular with ascetics. Thandai, a drink made with cannabis, almonds, and milk, is essentially drunk by the devout. This is so because cannabis is said to have been very dear to Shiva. The Puranas contain many stories and legends describing the origin of this festival.
According to one, during the Samudra Manthan, a pot of poison emerged from the ocean. This terrified the gods and demons as the poison was capable of destroying the entire world, and they ran to Shiva for help. To protect the world from its evil effects, Shiva drank the deadly poison but held it in his throat instead of swallowing it. Because of it, his throat turned blue, and he was given the name Nilkantha, the blue-throated one. Shivratri is the celebration of this event by which Shiva saved the world.
oh. thtas the case
So, this particular day, I mean on mahashivratri.. shiva drank and held the poison in her neck.
Very informative and helpful article.