Simply "Good Night" originating from 90's slang where the rule is to basically take the first letter of the word you wish to emphasize, and place it in front of "iggity." Then you would take your original word, and place it after the "iggity" you had created. It is common to see the original word dropped off once people knew what they were talking about, or it had become more "cool."
-also commonly used, but more ignored than niggity was "tiggity tight"
Evolution: niggity night
Person 1: night dude
Person 2: Niggity