yap verb to talk incessantly UK,1886 The term existed in this sense in C19 English dialect, and then independently arose in the US in the 1920s.
They’re special shoes, and I needed them now. And quit your yapping. I’ll get you there on time. — Max Shulman, TheManyLovesof DobieGillis, p. 188, 1951
When women get together, we sometimes drink, often eat, and always yap. — Anka Radakovich, TheWildGirlsClub, p. 4, 1994