Wearing a considerable lack of clothing when being outside on a cold day. The phrase also implies that the person seems to be unaffected by the chilly elements around them. The term Nord is derived from the Nordic race in Skyrim who possess fifty percent resistance to frost.
Sam: I'm just going to wear this sleeveless shirt outside.
Oleg: It's twenty degrees outside. You're gonna freeze.
Sam: I don't care. I'm going Nord.