A 1982 film directed by Brian Apsted, written by Jack Rosenthal and funded by Channel 4. The story, which is based in the late 1940's, centres around the Donald Bradman obsessed Alan 'Quack, Quack' Duckman, played by John Albasiny, and his crush on his classmate, Ann, played by Abigail Cruttenden. He spends all of his time dreaming of a way in which he can steal a kiss from her, before being presented with the perfect opportunity when she co-stars in the school play with him.
The films title is derived from the 'secret' password greeting between Alan and his friends, in which one party starts by saying with 'P'tang Yang Kipperbang', and the other responds with 'Uuungh'.
If you are after a copy of this bizzare coming of age tale, it is a little awkward as it has been deleted, but it is possible to track down the play that the film is based on:
Rosenthal, Jack. "P'tang, Yang, Kipperbang and other TV plays". London: Longman, 1984. ISBN 058222389X.
And yes, this was primarily noded due to its slightly odd title