About 13 minutes into I Am Legend Robert Neville has a flashback where he starts to rescue his family. While he loads them into the car, the camera cuts to two soldiers and one says to the other "Can't get used to the new rags." and makes a jerking motion across his face.
What is he talking about?
I think the soldier says, "I can't get used to the new regs" as in regulations. It's referring to Neville's (Will Smith's) beard that he has in the flashback. The "new regs" are likely to prohibit shaving with a razor in order to prevent open sores that could lead to infection by the virus.
He's referring to "new regs," as in Army regulations. Specifically, Will Smith's facial hair, which under current military regs, is not allowed unless you have a shaving waiver. I think this line was written into the movie to explain Will Smith's facial hair, which was easier than waiting for it to grow out for the later sequences (possible due to Will Smith's availability conflicting with other projects.)
Maybe the new "rags", meaning new gear, clothing(ACU uniforms were not really new at the time), maybe helmets? They weren't using normal GI MICH/ACH helmets and the movie i think was set a couple years in the future, maybe the seen helmets were thought by the costume designer to be better as they looked more advanced than the current issue MICH/ACH helmets("old" rags). But the facial hair thing makes a lot of sense too
