Half of wrong jabs uncovered -- targeted group may get this (2-4)
I believe the answer is:
in-joke
I'm afraid I can't explain this answer.
Can you help me to learn more?
(Other definitions for in-joke that I've seen before include "Exclusive gag?" , "Humour understood by a small group" , "Humour exclusive to a small group" , "Gag understood only by a small group" .)