I came across the amazing advert below which clearly shows that keeping mum over sexual violence acts is not the right thing to do. We should rather speak up and help put a stop to such. Follow the hashtag #WhoWillYouHelp to learn more on this. While these guys are in Canada, the principles apply all over the world especially in Africa.
You must not witness any form of sexual violence and keep quiet about it. Do what's right and speak out against such or lend a helping hand to the victims asap.
If you know of any such acts of sexual violence, kindly contact organizations like Stand To End Rape and/or the many more like it around Nigeria.