Our spies say security has been "beefed up" for Sarah's appearance.
And get this ... We found out the song Bristol Palin and Mark Ballas will dance to -- in front of Mama Palin. It's Three Dog Night's, "Mama Told Me (Not to Come)." Classic.
We're told Bristol will wear glasses and a conservative outfit but tear off her clothes mid-dance ... just like in the old days.