The missing word in Soft Cell's “Tainted Love” lyric is “you,” completing the song's direct address to the person at the center of its troubled relationship.
Soft Cell's version was released in 1981 and became one of the defining synth-pop recordings of the early 1980s. The song was originally recorded by Gloria Jones in 1964, but Soft Cell transformed it with stark electronic production, a dramatic vocal, and a darker atmosphere.
The composition was written by Ed Cobb, and the lyrics portray a relationship that has become emotionally damaging. The speaker describes trying to escape the cycle, which gives the opening line its sense of urgency. Soft Cell's recording was issued as a double A-side with “Where Did Our Love Go,” a Supremes cover.
The supplied alternatives are different pronouns, but “you” is the canonical answer. The line addresses the same person described throughout the song, so a fair quizmaster would not accept “him,” “her,” or “them” as substitutions.