Halahala

In Hindu mythology, the name of the
deadly poison produced when the
gods and demons churn the Ocean
of Milk. The gods and demons churn
the ocean to produce amrta, the nectar
of immortality. Yet their action produces not only the amrta, but also its
antithesis, the halahala poison. This is
an event of great peril, since if left
unchecked this poison is so powerful
that it will destroy the earth. The poison is neutralized by the god Shiva,
who holds it in his throat without swallowing it. The poison turns his throat
blue, hence one of his epithets is
Nilakanth, “the blue-throated [one].”
See also Tortoise avatar.