S'il vous plait, Qu'est-ce que c'est le Francais pour "je ne sais quoi"?

Reminds me of a very funny exchange in Marianne Ackerman's play, L'Affaire Tartuffe, or The Garrison Officers Rehearse Moliere. There the garrison officers are, rehearsing Moliere, and I believe they had to have a soldier stand in for one of the officers who couldn't be there (not positive that was the situation, it's been awhile since I saw the play!).

One officer reads his line and the soldier reads his response:

Soldier: Qwoy?
Officer: (correcting the soldier) Qwoh.
Soldier: What?!

Hm. Maybe it's funnier live....I still love it - an exchange that consists of the same word repeated three times with different nuances and in two different languages...!