The Famous badge is determined by the number of friends a user has, as follows:

• Add 10 friends to get a bronze badge.
• Add 50 friends to get a silver badge.
• Add 100 friends to get a gold badge.
• Add 500 friends to get a ruby badge.

Please click the following link for more details about the badges you can earn and their requirements:
https://blog.jawaker.com/jawakerbadges-en/