You always hear people referred to as the "th" member of a band or project. Like when someone refers to one of the 20 or so people who've been called the fifth Beatle. It's usually a producer or artist, someone heavily involved in the band's creative process. I don't personally know the guys in Arbitron, a Seattle duo influenced by the likes of Jesus Lizard and Mclusky, but it sounds like their "rd" (third member) is their drug dealer. And I mean this in the best way possible.