This is a bowdlerism! That is to use a similar, nonsense word in place of an offensive word. "God-damnit" -> "Gosh-darnit" "Oh my God" -> "Oh my Gosh" "Fuck" -> "Freak", "Frack", or in this case "Frap" "Shit" -> "Shh", "Sheep", "Ship", "This" There's lots of examples, and you can probably come up with your own. My fiancee, for example, always says "Gosh" and "Ship" instead of other words.

As Mr. A says, "frapping" is a substitute for a "bad word." The person may have actually said "frapping," or the writer may be softening what was actually said. Either way, "bad words" are often used without any literal meaning, simply to intensity the feeling of a sentence. The idea is that you do not use "bad words" until your emotion becomes so intense that you have lost control. Therefore, "bad words" convey the idea that the speaker feels very, very strongly about something. "The f-word" often conveys hostility or anger. "Barreling" conveys a sense of uncontrolled speed. Thus, it means: he's coming at me much too fast, he shouldn't be doing that, I am both scared and angry about it.