This is something that's puzzled me for years. On Tired of Sex, there is an instrument in the background supplying most of the backing beat. I've always thought it was a synthesizer, but lately I've been thinking maybe it's a guitar. Synth makes sense because TOS was originally a SFTBH song, which all had a synth base. But when the song is played live, they use a guitar, and the sound is similar…