The word "wicked" which means really or very, is first used in England as an adverb in 1980.
It is considered as slang which has multiple meanings in various regions around the world.; from "cool" to "hellish", often connotes something is excellent.
You can find its frequent use in Harry Potter series.
You can read more about the origin here : https://owlcation.com/humanities/Wicked-Slang-Origin.
Have a nice day,