Shove this in your Rails 3 config/initializers/ to raise exceptions on bad mass assignment attempts

mass_assignment_sucks.rb

unless Rails.env.production?
  module ActiveModel
    class IllegalMassAssignment < StandardError
    end
  
    module MassAssignmentSecurity
      module Sanitizer
        def warn!(invalid_keys)
          raise ActiveModel::IllegalMassAssignment, "You attempted to mass-assign: #{invalid_keys.join(', ')}"
        end
      end
    end
  end
end