内うち輪わネタ

noun

inside joke; private joke

A joke or reference understood only by a small group, such as friends or colleagues. Often used in casual conversation.

• あの話はなしは内うち輪わネタだから、他ほかの人ひとにはわからないよ。

  That story is an inside joke, so other people won't get it.

• 彼かれらの会かい話わは内うち輪わネタばかりで、ついていけなかった。

  Their conversation was full of inside jokes, and I couldn't follow it.