from russian 'yes', used with the well-known "retard entonation", means "yes, what else?" meaning the answer is so obvious that any retard would know… and all the retards speak russian, it implies…
So, it's really a kind of insult to the russians coming back from… daaah! what else?
the Cold War days, when they were the Evil Ones.
(At least
that's what I… grasped, if you will,
the first time I've heard it… but not being english my mother-tongue, I'm probrably wrong)