gistfile1.rb

class Foo
  def bar
    baz = 'something'
    baz + what_with_context(:something)
  end  
end

module Wat
  def what_with_context(id)
    instance_exec(&Huh.some_method)
  end
end

module Huh
  def self.some_method
    lambda do
      " +++ #{baz} +++ "
    end
  end
end

Foo.send(:include, Wat)

foo = Foo.new
puts foo.bar