少年先锋队 (Shàonián Xiānfēng Duì), The Young Pioneers, is the children’s branch (ages 6-14) of the Communist Party.
Many Chinese schoolchildren wear red neckties - they are the symbol of membership, and highly treasured by the wearers. Since many schools require students to wear it, many Chinese adults have ambivalent memories of the little stands outside many primary schools where forgetful students would buy replacements for 25 cents apiece.
The organization has an elaborate officer ranking system with Small Team Leaders (overseeing a row of students in a classroom), Middle Team Leaders (class prefects, overseeing a full homeroom), and Big Team Leaders, of which each school only appoints a few.
Appointment relies on grades and on how well liked the students are by their classmates. The highest-ranked get to go to the Great Hall of the People in Beijing for an annual consultation with the actual government.
Not just a fashion thing. Wikimedia Commons