the female opposite of a cougar...a younger woman that goes for grossly older men
the silver fox refers to the graying hairs and the fox being the male being desired after. The hunter obviously refers to the younger woman desiring the man.
Guy 1: Did you see the guy that Lola was with last night?
Guy 2: Ya that guy was totally ancient! She's a freakin silver fox hunter man...
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.