Learn Hardcore Japanese: kinyou no yoru ni tomodati to piza wo tabe nagara geemu wo simasita. - On Friday night I played games with a friend while eating pizza.

金曜きにょう　の　夜よる　に　友達ともだち　と　ピザ　を　食たべ　ながら　ゲーム　を　しました。kinyou no yoru ni tomodachi to piza o tabe nagara geemu o shimashita.

On Friday night I played games with a friend while eating pizza.

Breakdown of kinyou no yoru ni tomodachi to piza o tabe nagara geemu o shimashita.

をo

direct object particle

Questions & Answers about kinyou no yoru ni tomodachi to piza o tabe nagara geemu o shimashita.

Why is it 金曜 instead of 金曜日?

金曜（きんよう） is just a shortened, more casual way of saying 金曜日（きんようび）, “Friday.”

金曜日 = full, neutral form (fine in writing, speech, anywhere)
金曜 = clipped form, common in speech, notes, schedules, casual conversation

Meaning is the same. In this sentence, you could say 金曜日の夜に instead of 金曜の夜に with no real change in meaning; 金曜 just feels a bit lighter / more conversational.

What is の doing in 金曜の夜?

の connects a noun that describes or modifies another noun.

金曜の夜 literally = “Friday’s night” → “Friday night”

So:

金曜 (Friday) + の
- 夜 (night)
  → “the night of Friday” → “Friday night”

This pattern is very common:

日曜の朝 – Sunday morning
夏の夜 – summer night
日本の映画 – Japanese movie (movie of Japan)

Why do we use 夜に and not just 夜 or something like 夜で?