Code from blog post on anonymizing sensitive user data

anonymizer_source.rake

task :env_checker do
  unless Rails.env.development?
    puts "Not in development environment, exiting!"
    exit 1
  end
end

namespace :app_name do
  desc 'Anonymize user, company, and location information'
    task :anonymize => [:environment, :env_checker] do
      User.all.each do |user|
        genders = ['male', 'female']
        user.update_attributes!(
          :born_on => rand(50*365).days.ago 
          :email => (rand(1000) + 100).to_s + Faker::Internet.email,
          :first_name => Faker::Name.first_name,
          :gender => genders.rand,
          :last_name => Faker::Name.last_name)
      end

      Company.all.each do |company|
        company.update_attributes!(
          :description_html => Faker::Company.catch_phrase,
          :name => Faker::Company.name,
          :twitter_username => Faker::Internet.user_name,
          :url => 'http://' + Faker::Internet.domain_name)
      end

      location_array = Location.all.inject([]) do |result, location|
        result << [location.lat, location.lng]
      end.shuffle

      Location.all.each do |location|
        lat, lng = location_array.pop
        location.update_attributes(
          :city => Faker::Address.city,
          :extended_address => Faker::Address.secondary_address,
          :lat => lat,
          :lng => lng,
          :phone => Faker::PhoneNumber.phone_number,
          :postal_code => Faker::Address.zip_code,
          :state => Faker::Address.state_abbr,
          :street_address => Faker::Address.street_address
        )
      end
    end
end

To generate your own phone format, you can use Faker.numerify("###-###-####")

See more at https://github.com/yyyc514/faker/blob/master/lib/faker/phone_number.rb#L5