Dang this author has a really good grasp on English. "Slippy McSlipperson" is the sort of thing that you don't get just from studying textbooks, you need to really immerse yourself within a culture to get that kind of jargon.
@Kellizer-Levvit
Wakabayashi-senesi actually admitted his knowledge of the English language is almost nonexistent.
Apparently he uses the aid of a translator (/u/AsianMixMaster on Reddit) to adapt his original Japanese puns to more suitable English counterparts.