(now chiefly Canada, US, Ireland, Northern British) past participle of get inside someone's pants

(informal) Something is endemic, and not the result of outside influence or interference.

The characteristic behavior of insiders / Attitudes or behavior which are preferential to insiders

(informal) Characteristic of an insider; especially, reflecting an insider perspective.

(informal) Like an insider; familiar with inner knowledge, in-jokes, etc.

The status of being an insider.

Characteristic of insiders.