NotClass

not_class.rb

class Object
  def not
    NotClass.new(self)
  end
end

class NotClass < BasicObject
  instance_methods.grep(/^[^_]/).each { |m| undef_method m }

  def initialize(object)
    @object = object
  end

  def method_missing(name, *args, &block)
    !@object.send(name, *args, &block)
  end
end

puts nil.not.nil?
puts 1.not.eql?(2)
puts [1, 3, 5, 7, 9].not.any? { |i| i % 2 == 0 }

require 'benchmark'

Benchmark.bm do |x|
  x.report { 1.upto(1_000_000) do; 1.not == 2; end }
  x.report { 1.upto(1_000_000) do; 1 != 2; end }
end

       user     system      total        real
   0.302335   0.001475   0.303810 (  0.303833)
   0.035334   0.000051   0.035385 (  0.035446)