'Chill Will' or 'Chill Will Factor' is generally just an exclamation of the temperature being unusually cold or chilly. The word derived from cold making your 'bits' freeze, hence chill will.It can also be used to describe a flaccid penis or someone who is an idiot.
1. "Should have brought my jacket, man."
"Oh yeah, theres a bit of a chill will factor"
2. "Mike has a chill will"
"No wonder nobody wants to do him"
3. "Dave Chapelle is a bit of a chill will"