grow teeth
v. phr.— «The Monster grew teeth today.…It was very testy and I tried to force a few shots that didn’t come off.» —“Nicklaus hopeful something in wind” by Steve Hershey USA Today Mar. 4, 1991. (source: Double-Tongued Dictionary)
Further reading
Authors often go through several working titles before settling on one. F. Scott Fitzgerald’s The Great Gatsby (Bookshop|Amazon) was originally Trimalchio in West Egg, Trimalchio being an ostentatious nouveau riche character in an ancient Roman work...
Susan from Virginia Beach, Virginia, shares the phrase her mother used when the kids refused to eat: It’ll grow hair on your back teeth. This supposed motivator likely blends two older traditions: a German idiom, Haare auf den Zähnen haben...