oop.rb

module TestConcern
  extend ActiveSupport::Concern

  module ClassMethods
    def foobar(a,b,c)
      puts "doin sum cool shiz in hurr liek: #{a}, #{b} and #{c}"
    end
  end
end

class TestClass
  include TestConcern
  foobar("some", "cool", "args")
end