League of Legends is a hugely popular multiplayer online battle arena game from Riot Games, and its client is the program players open to log in, queue for matches and pick champions. The button click is one of the everyday interface sounds from that client, rather than a line of dialogue or a musical theme. Because millions of players hear it while waiting in lobbies, it has become instantly recognisable in gameplay videos, streams and short memes, where a single click can signal that a match is about to begin.