Rather, the whippets people use to get high are the same thing that makes the whipped cream come out of the spray can. The "chargers" that make the can work are bought and sold separately by drug users without the whipped cream.
Maybe the writer didn't understand that. But who knows? Maybe the woman with the whipped cream can was just that out of it.
I recall girls (always, guys just didn’t do it for whatever reason) doing “whippets” in the grocery store when in high school and college. Evidently it was quite a rush, flushed face, wide grin, involuntary “wooohooo” and all. So, at one time it “worked” with the whipped cream cans, saw it first hand.
Photo at link shows whippets and dispenser. No whipped cream in evidence. Or photo for determination of verdict.