大盤振る舞い (hiragana おおばんぶるまい, romaji ōbanburumai, historical hiragana おほばんぶるまい)
/ohobanburumahi/: *[opobanburumapi] → [oɸobanburumaɸi] → [owobanburumawi] → [oobanburumai] → [oːbanburumai]. 大盤 is ateji; was originally 椀飯. Medial voicing due to compounding.