To inhale the vapors produced by heating heroin (or other opiates) on foil in order to obtain a high; to engage in this method of drug use.
2.
USUKGeneral Englishinformalslang
To pursue an elusive or diminishing high or thrill, often by repeating risky or self-destructive behavior in an attempt to reproduce an initial peak experience.
Figuratively, to chase after an unattainable or illusory goal, often at great personal cost.