Originally meaning 'virgin' to folks of The Shire, 'pippinfresh' is something rare and precious, often used in sexual contexts. It has now expanded its meaning to anything elusive, and generally good.
Mr Frodo, Rosie is pippinfresh to say the least.
A term used amongst Hobbits and adolescent males, to signify something as good.
That butt slut is rather pippinfresh in the sack.