One who uses heroin only on the weekends, chipping is the act of recreational heroin use. This term was widely used in the 1960s and 1970s and applies only to the use of Heroin. One who chips is known as a chipper.
Using a sharp object for chipping small quantities of cocaine base from a rock of cocaine; instead of smoking the whole thing and immediately ruining your life.
1. I've been chipping by shooting smack every second Friday, I don't want to overspend
2. I broke 4 ribs by jaywalking on a highway falling in front of a car while chipping