On this dvadasi, following Sayana EkAdasii, Lord Vishnu takes rest on the milk ocean, where he remains sleeping for four months called Chaturmasya.
This pastime is enacted in the following manner. The Lord may be brought on procession to a lake or pond, where one can perform full worship, and then bathe the Lord in the lake saying:
sese paryanka varye'smin phana
sveta dvipantare deva kuru nidram namo'stu te
Oh Lord, in Svetadvipa, please take rest
on your bed in
the form of sesa-naga with his jewelled hoods.
Let me pay my respects to you.
After the puja, and kirtana, charanamtra and prasadam should be distributed.
Then the deity should be brought back to the temple amid all pomp and ceremony.
In some places they have other wonderful ceremonies, such as Udupi where
the Paraya Swami anoints everyone with Tapah
Mudra - heat brands symbolically everyone then wears the branded weaponry
of Lord Vishnu upon their/our bodies. Gaudiya Vaishnavas, it is mentioned
in Prabhupada's purport to Chaitanya Charitamrita commenting on the contents
of Hari Bhakti Vilas 15th Chapter, that "There are also descriptions of
branding the body with the symbols of Vishnu"(A.C. Bhaktivedanta Swami
Prabhupada. Chaitanya Charitamrita Madhya-lila 1:35. purport).