John,
I remember this question popping up a couple of years ago on one of the scale modeling forums. You are wright about #1 đù mẹ mi being cuss words. I think it translates roughly as:
#1 mother f*cker
I am no expert on vietnamese, so I checked each word on online dictionaries/translation tools just to be sure:
đù: to f*ck, to stuff
mẹ: mother
mi: I have no idea as there are so many meanings depending on how it is written
I guess the crew of this Snake didn't explain the brass what the "nickname" translated to :)
Marko