おなじんじゃう
お馴染んじゃう
onajinja u

Godan Verb (u)
no-Adjective

The completive aspect (contracted form) - indicates completion or regret of おなじみ

1. To get used to; To become familiar with; To be well-known (and thus predictable/regrettable)

Completed Action
Colloquial
Usually Written in Kana