What does ALT+255 mean?

ALT+255 meaning in Urban Dictionary

ALT+255 is extremely difficult to define because there isn't actually almost anything to define. Its a void of unkown possibilities and endless nothingness. ALT+255's are really easy to create, you are able to do it compose today, it's name is also the directions to create one. So check it out, create your very own absolutely nothing these days!