Yes Max, I can identify with that. I recall my mothers' reaction when I telephoned her during one of my NZ holidays to tell her I was going to Whakapapa.

There was a Maori comedian who had a character called "Abe Whakatawhainau" - if the surname is pronounced properly, and fast, it sounds exaclty like "F*cked If I Know" - although that can't quite match the incestuous nightmare you gave your poor mother!
(As an interesting aside, the English word that comes closest to translating "whakapapa" is genealogy) Coincidence?