Cyndi Lauper’s troubled son name dropped his legendary pop-star mom and her hit single “Girls Just Want to Have Fun” when he was arrested on gun possession charges stemming from a Harlem shooting earlier this year, new court papers show. Aspiring rapper Declyn “Dex” Lauper begged police to call his mother after the discovery of a loaded gun in his fanny pack on Feb. 7 — and even tried to make sure they knew who she was by reminding officers of the singer’s trademark 1983 hit. “I grew up, my mom is Cyndi Lauper, Girls Just Want to Have Fun,”...