It all started with the “Great Shape” Barbie in a turquoise Spandex gym outfit and striped leg warmers. Yes, there is a 33-year-old Singaporean man who has been collecting Barbies for 20 years. Jian Yang, who calls himself a “toy nerd,” has more than 6,000 Barbie dolls and 3,000 dolls of other kinds—on which he’s spent at least $392,000—spilling out of cabinets and shelves in his home. His friends have come to support the strange obsession. His parents ... well, they merely accept it.