Who Can It Be Now? is a 1981 song by Australian band Men at Work. The track became one of the group's signature hits, helped by its memorable sax line and nervous vocal delivery. Online, short clips from the song are reused as reaction audio for door knocks, surprise arrivals and intrusive messages. It still works well in memes because the title itself sets up the joke instantly, so creators can convey suspicion or annoyance in just a few seconds.