Usage: "It's bare chappin in this classroom, Miss. You never heard of radiators?"
As we're mittens-deep in autumn proper, this is a term you will hear more and more, often stuttered in an exaggerated faux-frozen delivery to really ram the point home. That very serious point being that it's a bit chilly out - perhaps prefaced with "bare" (meaning "very" - consult Yoofspeak #13) for maximum impact. "Chappin" comes from the term "chap", as in the reddening of skin through exposure to the cold which most females of the Yoof tribe nowadays address with a flavoured chap stick (cherry if they're Katy Perry fans). Of course, males tend to avoid any kind of preventative solution and seem to spend all their time coming up with catchy new words to describe their pain instead.