Varaha Dvadasi: Appearance of Lord Varahadeva
Dvadasi is the twelfth day of the waning or waxing moon (dva, "two," dasi, "tenth"). In the Vedic, lunar calendar, dvadasi follows Ekadasi, a day customarily set aside for exclusive focus on spiritual activity and fasting—at least from grains and beans.
Fasting for Ekadasi is considered incomplete unless one breaks fast at the proper time the following day, dvadasi.
Varahadeva is Krishna's boar incarnation. He assumed the form of a boar to lift the drowning planet Earth from the Garbhodaka Ocean with His tusks. The demon Hiryanyaksha had thrown the planet Earth into this ocean, but the Lord stabbed the demon with His tusks and saved the Earth.
a few verses from Srimad-Bhagavatam, Third Canto, chapter 13:
"Brahmā thought: While I have been engaged in the process of creation, the earth has been inundated by a deluge and has gone down into the depths of the ocean. What can we do who are engaged in this matter of creation? It is best to let the Almighty Lord direct us.
O sinless Vidura, all of a sudden, while Brahmā was engaged in thinking, a small form of a boar came out of his nostril. The measurement of the creature was not more than the upper portion of a thumb.
O descendant of Bharata, while Brahmā was observing Him, that boar became situated in the sky in a wonderful manifestation as gigantic as a great elephant.
Struck with wonder at observing the wonderful boarlike form in the sky, Brahmā, with great brāhmanas like Marīci, as well as the Kumāras and Manu, began to argue in various ways.
Is this some extraordinary entity come in the pretense of a boar? It is very wonderful that He has come from my nose. . ."