本命 (běnmìng) is a fascinating example of a traditional concept being repurposed for modern pop culture.
You will encounter 本命 in two very different conversations.
This usage is common in family settings, especially with older generations, around the Chinese New Year.
This usage is extremely common online, especially on social media platforms like Weibo (微博), Bilibili (哔哩哔哩), and Douban (豆瓣).