This happened to my old pal, Judy Leitze, several years ago, back in Chicago.
Judy was walking home from the neighborhood grocery store, past one of the "projects" -- a big low-rent apartment building put up by the city to house the poor. As you might guess, the building turned the neighborhood into a "tough" district, but Judy didn't mind; she lived in an older apartment building further down the street. Anyway, it was just after sundown and the usual crowd of teenagers were hanging out, trying to act tough before they had to go in for dinner.
This evening there was a knot of maybe four teenaged Black boys hanging out by the corner, and when they spotted Judy they started hooting the usual scare-the-Whiteys crap. You know: "Hey mama, I got what you want!" accompanied by disgusting noises, intended to make the passers-by scamper away and boost the egos of punks.
Ah, but Judy knew the territory, and knew how do deal with such. She turned around, pulled herself up straight and shouted back, in her best Parental voice: "Young man, does your mother know you hang out on the street-corners after dark, shouting dirty words at strange women? Because if not, then somebody ought to tell her. Now, I know you live in that apartment building there, and it wouldn't be hard to find out--"
That was as far as she got. The boys turned around and ran like gazelles for home. In a few seconds, they'd vanished. Judy walked on home, chuckling.
"Always remember," she said, when telling the story, "That all these would-be punks have mothers -- mothers who are usually their only source of income, food, shelter, or anything else. The biggest threat you can throw at them is I'll Tell Your Mother On You."
'Twas demonstrably true; I never saw any other bunch of punks in that neighborhood bother Judy again.