Butt fluffies are those
mounds of
lint/
hair that roll up into
pseudo-
dust bunnies between one's
crack.
Men seem to develop them more because of the increased
hair content of their own lower back and bum. The
electrostatic forces generated in daily movement allow the dust/lint/loose hair particles/strands to clump into mountains of fuzz.
Oddly enough, women who have nearly hairless bums and lower backs still may find that they produce large quantities of butt fluffies. This can be attributed to loose and long head hairs (hence pertaining to women with long enough hair) making their way down the back to the bum.
How do I know these things?
1) I clean my own ass
2)
Women tell me these things when I ask them.