Green’s Dictionary of Slang

1. (drugs) a person who occasionally takes illegal drugs, esp. injectable narcotics.

1936		D. Maurer ‘Argot of the Und. Narcotic Addict’ Pt 1 in AS XI:2 123/1: joy-popper. A person, not a confirmed addict, who indulges in an occasional shot of dope. However, joy-popping is usually the beginning of a permanent addiction.
1949		N. Algren Man with the Golden Arm 24: They called those using the stuff only occasionally ‘joy-poppers’.
1952		Lannoy & Masterson ‘Teen-age Hophead Jargon’ AS XXVII:1 27: JOY POPPERS, n. Inexperienced users of drugs.
1953		W. Brown Monkey On My Back (1954) 52: He admitted that he used heroin ‘occasionally’ [...] declaring that he was only a ‘joy-popper’ – an occasional user.
1956		‘Raymond Thorp’ Viper 78: Our clients were [...] not far enough gone to be registered [as addicts]. We called them ‘joy-poppers’.
1959		J.E. Schmidt Narcotics Lingo and Lore.
1971		E.E. Landy Underground Dict. (1972).
1979		‘Iceberg Slim’ Airtight Willie and Me 74: The legions of junkie joy poppers who had fouled her rotten with their shooting galleries.

2. a delight.

1961

H. Ellison ‘This Is Jackie Spinning’ in Gentleman Junkie 68: And tonight’s show is a real joy-popper!