As you all know Blow was on the setlist for a bit while she toured, however what's important to notice is the song mixed in with Blow. A song by the girl group Vanity 6
A group put together by none other than Prince himself. The formation of said group was part of a highly sexualized vision Prince had in which the women would dress provocatively and sing sexual songs.
Denise Matthews was made the front woman of the group after Prince took an interest in her. The group's success was short lived and Denise now known as Vanity left the group to pursue solo endeavors.
Eventually she almost OD on crack and became a born again Christian. She passed away during February this year, 2 months later her mentor and ex lover Prince passed away. The tour paid homage to prince in multiple ways from purple rain to the beautiful ones. Nasty Girl was yet another tribute to a man some would consider Beyoncé's mentor/idol.