The little boyfriend who buys sour plum soup is a joke that describes boys. Meme is an Internet term. The Internet term "sour plum" means that girls are cute, and it also means that boys are easily jealous. Sour plum juice, also known as sour plum soup, is a folk drink that relieves summer heat. It has the effects of promoting body fluids, appetizing, relieving heat and quenching thirst. Our country has had sour plum juice a long time ago. "Tugong Plum Jian" recorded in ancient books is a kind of sour plum juice.