When a fat chick sits on your fist with a thong on. The thong gets tangled in your paw creating a veritable web/nest. When you pull your fist out you make her dog dump on her chest and entwine the thong in the poop. The dog thinks the fat chick is the "bear" intruding on his territory so he attacks. Hopefully by this time you have untangled your paw and can nut in the beleagured fat chicks face, hark the reference to the Batslavian ice cream steam roller. The knuckle comes into the equation when you sprinkle pubes on her grill and punch her in the face. The pubes form a beard making her look like a bear you just fought.
"Big Betsy was trying to chill on my shipmate last night and I hit her with the Batslavian Bear-Knuckle which made her heart smile in jubilation...."