example.rb

class ArrayProxy < BasicObject
  def initialize(proxy_array)
    @proxy_array = proxy_array
  end

  def <<(arg)
    ::Kernel.send(:puts, "I'm in ur methodz, playing wiz ur args")
    @proxy_array << arg
  end

  def method_missing(*args, &blk)
    @proxy_array.public_send(*args, &blk)
  end
end

class Foo
  def bar
    ArrayProxy.new([])
  end
end

Foo.new.bar << "woo"