The first thing that came to mind when I read that was: what are the intonations...?! Then I went through them all and yes: Mo(B-A) mun (T) tai (B) (to put it crudely)Ladette said:Momentai:
It means "No Problem" in Cantonese, I stole it from Digimon Tamers Terriermon. I use it as a replacement for relax.
OT: Currently 'Flaps' (with a capital F) since it is the (transient) nickname for a colleague who gets amusingly annoyed at just the mention of the word 'flaps'.