Something that is either as wonderful or as disgusting as female genitalia. May have a pejorative or positive connotation depending on context and on the ennunciator's views on female genitals in general.
1. Damn Freddy, you smell cuntasitic, is that the new axe cologne?
2. Damn Freddy, your breath smells cuntastic. You need to brush those things. Ugh.