From merriam-webster.com:
Main Entry: 1wick·ed
Pronunciation: \ˈwi-kəd\
Function: adjective
Etymology: Middle English, alteration of wicke wicked, perhaps from Old English wicca
Date: 13th century
1 : morally very bad : evil
2 a : fierce, vicious <a wicked dog> b : disposed to or marked by mischief : roguish <does wicked impersonations>
3 a : disgustingly unpleasant : vile <a wicked odor> b : causing or likely to cause harm, distress, or trouble <a wicked storm>
4 : going beyond reasonable or predictable limits : of exceptional quality or degree <throws a wicked fastball>
— wick·ed·ly adverb
I think 1 describes Caj's sense of humor properly. 3a and 4 also fit. I see no misuse of the word.