Frindle is an American children's novel written by Andrew Clements. The story centers on a 5th-grader named Nick who invents a word—"frindle"—that winds up causing quite a stir in his school and, ultimately, beyond.
Nick has a rather tough, white-haired old English teacher named Mrs. Granger who makes no attempt to hide her love of words. While Nick is trying to get everyone to use his new word, however, Mrs. Granger is trying to stop it. Nick and the kids mention two nicknames for Mrs. Granger in the book.
The first one, initially appearing on page 16, is "The Lone Granger." This makes reference to a couple of facts about her: one, that she lives by herself, and the other being that she is fierce and intimidating like The Lone Ranger.
The second nickname, spoken by the Dave character on page 47, is "Dangerous Grangerous," referring to her propensity to punish the boys for getting out of line, from putting them in detention to making them wear their chewing gum.