gistfile1.txt

class Parent
   def foo
      puts "I'm a good parent."
   end
end

module Interloper
   def foo
      puts "I've got candy in the van."
   end
end

module NiceInterloper
   include Interloper
   undef foo
end

class FirstChild < Parent
   include Interloper
end

class SecondChild < Parent
   include NiceInterloper
end

FirstChild.new.foo # => "I've got candy in the van."
SecondChild.new.foo # => "I'm a good parent."