使用http referer或通过URL传递自己的参数来确定引用类别。第一种选择对我来说似乎更好。

这个

//check, whether a user does not access a page directly
if(isset($_SERVER[\'HTTP_REFERER\']))
{
    //get category object
    $category = get_category_by_path($_SERVER[\'HTTP_REFERER\'], false);

    //if category URL was passed 
    if(NULL !== $category)
        echo $category->name;
    //otherwise get your random category
    else
        echo get_random_category_function();
}
else
    echo get_random_category_function();

function get_random_category_function() {
    //code for generating random category
}