senior sisters cruise

Hi, my sister and I are on the same Dec 5, Oasis Cruise. My sisters' first, My...lost count but my last cruise was in 2005! A lot has changed. Those were the days when Everything was included My question is, I heard there are 2 formal nights and maybe a Disco theme night. Anyone have any info? I need to know if I need to bring my hot Pink spandex bell bottoms and disco ball earrings!LOL