This Banyankole tribe from Southwestern Uganda. In this tribe when it comes to marriage, the aunts to brides have special role to play by sleeping with would-be husband to their nieces to test their potencies.
This is to make sure they are potent. The whole idea of this tradition is to ensure their nieces virginity has been defended before being married.
The aunt also test if the bride is still a virgin before allowing the wedding to take place. Although, this outdated practice may sound weird but it shows how the people of Banyankole, particularly the Bahima tribe hold virginity in high esteem.