The Democratic Party of the USA played this 1979 song at its 2004 national convention.
One of the functions of a political party is to aggregate people – to bring them together. They are hoping to be able to bring together people of like minds, and enough people of like minds, for the purposes of seeking electoral victory. Political parties are institutions one can be a part of, to feel like they belong to something bigger than themselves.
To prove they are part of the family, typically individuals may purchase a membership in a political party of their choice. Many parties offer free memberships to youth. And by the way, many parties consider “youth” to be up to age 30.
Being a “card carrying” party member is an easy way to make new friends, with people whom you likely have much in common – especially, ideologically. In this way, the political party function of interest aggregation also has a social role.
There are many social functions associated with such participation, including conventions, events such as dinners and fundraisers, youth wings, coffee parties, even pizza and beer nights. Oh, and course, volunteering come election time.