There are a few versions of the Hitchhiker's Guide series, with slight differences here and there. (I'll read anything, by the way, and I do find certain passages from the series absolutely delightful, and I don't care what people might think or if they'll stop saying hello to me when they find out).
The book version that I have includes this passage:
"You're a jerk, Arthur Dent. A complete kneebiter."
In the audio version, the author reads:
"You're a jerk, Arthur Dent. A complete asshole."
The author (or his editor, anyway) must have figured that the word "kneebiter" would puzzle listeners outside of Great Britain (that rules the seas) - (or something) - and that "asshole" (or "arsehole") was more widely and readily understood. Personally I dislike the word "asshole" (or "arsehole") because it lacks subtlety and can mean altogether too many things.
But what the hell is a kneebiter? Or knee biter?