Unbearably cold, usually induced by a sudden change in temperature i.e jumping into a freakin' plunge pool in the arctic.
Bear Grylls: THIS is going to be chilly perkins *dives into epically cold waters*
Eskimo boy#1: Man, it's chilly Perkins out here!
Eskimo boy#2: Knows it bro! I think my nipples just fell off!