Is the Dragon King here? Come out and spray some water for us.
A new feature in QQ: In a group chat, the one who speaks most in one day will be awarded with a "Dragon King Medal"(the icon on Mokou's hand), which changes each day. It works fine in regular group chats, but it could look stupid in group chats designated for serious matters such as online course or work affair, since there is no way to turn this feature off. It definitely looks awkward when your lecturer or supervisor got awarded with this medal after a long speech.
This virtual medal also created a hint of privilege, although it really is just a medal. The original intention was probably to introduce a small sense of envy, thus encourage competetion, which leads to more activities in group chats. As you can tell, a "most talkative person of the day" medal sure is nothing to be envious for. Because of this, many netizens made corresponding memeticons and turned this into a joke. This particular one about spraying water is one of the mild ones, more naughty versions exist, like turning the medal to be a "public sex slave of the day" certification.
Dragon Kings in Chinese folklore are in charge of all kinds of precipitation in a region they're assigned to, and they do it by spraying water from their mouths, hence the spray water joke.