SZA‘s Los Angeles stint for her “Grand National” tour is off to a depressing start … the R&B star claims she persuaded a child to forfeit their fruity whippet at an In-N-Out parking lot!!!

The “Kill Bill” singer didn’t specify how old she thought the young fan was, but says she convinced them to hand over a can of SuperWhip strawberry-banana-flavored nitrous oxide, in exchange for a photo/video for their IG … where are the parents?!?

SZA says she’ll do everything in her power to help change the scenario, but ripped America for making drugs so marketable and alluring to children.

Call it using her massive influence for good … SZA and Kendrick‘s “Luther” collab is still the No. 1 song in the country after a whopping 13 weeks.