C# - Random Item in List

I have an ArrayList for ImageItem, and I want random my image in Repeater.
List<ImageItem> listImageItem = GeneralFunctions.GetImageItem(imgListIds, false);

listImageItem = listImageItem.OrderBy(x => Guid.NewGuid()).ToList();

Repeater1.DataSource = listImageItem;

Repeater1.DataBind();