A popular slang used in Taiwan PTT Bulletin Board System, which means that a man's penis expands and holds the erection. It mimics the sounds of traditional Chinese words "雞雞硬硬的" and the letters can be large or small, such as "ggininder".
The person who is a bit aloof when you first met him but when you know him he the the best of best supporting caring loving. If any of your friends is "guninder" you are lucky to have one loyal , livel , honest , funny , as well a full power house