Stands for 'hard nipple weather.' Used most often when a person's nipples are visible through their shirt.
"Did you see that girl's nipples? She definitely had a reaction to some HNW"
"Whoa look at his nipples... He must be experiencing some HNW"
"Whoa look at his nipples... He must be experiencing some HNW"
by ilikemoney1480 November 22, 2009