The goo card in the rice circle is the transliteration of Han Wenzhong's "sticking a card", which means decorating a small card with a sticker. It can be a physical card or a photo with many small stickers on it.
Mainly used by fans for collection. For most people, a small card is just an ordinary card with no value. But for girls in idolize, especially fans who like to collect small cards, a small card is printed with beautiful photos of their idols, so small cards are very valuable items in the eyes of fans.