pip-pip

Imitative of a short, high sound made by a bicycle or car horn.

pip-pip

1. (UK, informal, dated) goodbye
   • 1921, P. G. Wodehouse, Indiscretions of Archie, ch. XIII:

     "In that case," said Archie, relieved, "cheerio, good luck, pip-pip, toodle-oo, and good-bye-ee! I'll be shifting!"