Though I'm not certain; I believe Webster is trying to say "When it's bloody cold outside; put on your friggin' jacket." It's a basic concept; really it is, but I cannot seem to remember it from day to day.
Alas, I freeze my choochoos off every morning and curse the couch that, thanks to my lack of logic, is all warm and toasty. I wouldn't be surprised if I got home and the blasted piece of furniture is snuggling with my blanket, too. Jerk.