Green’s Dictionary of Slang

chippie v.1

also chippy, chippy around
[? SE cheap or chip v.2 (1)]

1. [1920s+] (drugs) to use narcotics, esp. heroin, only on an irregular basis rather than to be a habitual addict; thus chipping n.3

2. [1970s] in non-drug contexts, to work half-heartedly.