It doesn't mean anything. It's just a fun thing to say. A lot of rappers use stupid language like that. Like instead of "for sure," they say "for shizzle." Instead of "no doubt," you might hear "no diggity" or "no dizzle" or "no diggity doubt."
You might hear "How you diggity doin'?"
"Pretty wiggity well."
It has no meaning, and while ending stuff with -izzle is still somewhat common among ethnic youth or those who embrace their culture, -iggity is from the 80s and early 90s rap culture.
El siglo pasado, para darle más gracia a la exclamación "hot dog!" (¡qué bien! ¡maravilloso!), se metía un "diggity" -"hot diggity dog". De allí viene, creo.
Luego, está el vecino mujeriego de los Simpson, Glen Quagmire, quien dice "giggitty-giggitty".