we do what we must because we can

not_able.rb

module NotAble
  def not
    boolean_bizzaro_world
  end

private

  def boolean_methods
    methods.select { |m| m.to_s.end_with? '?' }
  end

  def boolean_bizzaro_world
    this = self

    Object.new.tap do |obj|
      boolean_methods.each do |method|
        obj.define_singleton_method method,
          -> (*args) { ! this.send method, *args }
      end
    end
  end
end

String.include NotAble

''.empty?              # => true
''.not.empty?          # => false

''.kind_of? String     # => true
''.not.kind_of? String # => false