gistfile1.rb

class Stweie

  ALLOWED_METHODS = [:methods, :method, :why]

  def hello
    'Hello'
  end

  class_eval do
    def why
      'WHY'
    end
    instance_methods.each do |method|
      undef_method method unless method_belongs?(method)
    end
  end

  instance_eval do
    def allowed_methods
      ALLOWED_METHODS
    end
  end

  def method_missing(method_name)
    puts "You've asked me to #{method_name}, but where are my money, BITCH?"
  end

  private

  def self.method_belongs?(method_name)
    ALLOWED_METHODS.include?(method) or method =~ /^__/
  end

end