Crotch-pheasant offensive noun
A small insect that lives on the bodies of humans and animals (especially of the sexual organs)
If you discover crotch-pheasants, you will certainly need to reconsider your personal hygiene.
Often used in plural.
The origin of this idiom is not clear.
Meaning absolutely certain or without a doubt
I am as sure as God made little green apples that Peter's the one for you, you two make a beautiful couple.