Based on your query, there are a few different "Vicky" stories, but here are the most prominent ones regarding a "fast" (diet/speed) context:
In The Fairly OddParents , Vicky is the antagonistic babysitter who acts so quickly in wrecking Timmy's home that it takes only a second, and she fools his parents easily. vicky fast
If you meant one of these specifically, let me know which one: The ? The Bollywood actor ? The cartoon villain ? Based on your query, there are a few