no no (cold cold)
sov sov (hot hot)
nco nco (miss miss)
mob mob (hurt hurt)
nqhis nqhis (crave crave)
why do we do this? 

I guess it's just an emphasis of "very" and "so very" which then makes "no
heev", "sov
heev", and so on optional or another way of saying the same thing in a calmer tone in comparison to No NOOOOOOOOOOOOO
OOOO and Sov SOOOOOOOOOOOOO
Vvvvvvvvvvvvvv
vvvv. I think if either is used, they have a different effect. That's only what I think.

Flipping Backwards. Say it in Hmong....... LOL. 
That's right. Forgot about that word. I always thought that was weird too. How did we come up with these words? Lol.