This track was intially introduced as being about 'knowing who your real friends are and when they're going to come to your gigs'. Thom soon simplified this to 'knowing who your friends are.' The song reflects Radiohead sense of humor; it contains many ridiculous lines about the CIA and the Marines.
Of the opening, Thom says, 'The sound at the beginning comes from this caterwauling mayhem outside this hotel in the States. There was this guy training these eight-year-old kids, who were parading up and down with all these differents instruments. The guy had this little microphone on his sweater and was going: 'Yeah, keep it up, keep it up.' So I ran out and taped it.'