JPF is an acronym for "Just Poking Fun", and is synonymous with the over used "Just Kidding". The opposite of JPF is INPF which means "I'm not poking fun".
-I really don't like those shoes.
-I really don't like YOU! JPF, don't be mad.
jam-packed-full, filled to the brim.
M: I've been deleting a lot of my music from my itunes library lately.
A: Why's that?
M: Because my laptop is JPF!