Every single one of your friends will add a contact to their phone, with 1: The new phone number, 2: Your real life name. They'll then go and share that contact

Every single one of your friends will add a contact to their phone, with 1: The new phone number, 2: Your real life name. They'll then go and share that contact list with a dozen different apps, including Facebook and Whatsapp. Some of them will add your email address, birthday, and home address to that contact as well.