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.

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?

に is the standard particle to mark a specific point in time.

夜に = “at night / in the evening”
金曜の夜に = “on Friday night”

You often use に for:

specific days: 金曜日に, 明日に
specific times: ７時に, 午後に
specific time expressions: 夜に, 午前中に

You can sometimes drop に in casual speech with time words (especially days):

金曜の夜、友達と… (no に)

That’s still natural. But 夜で would be wrong here; で is more about location / means / situation, not a simple time point.

What does 友達と mean? Is と “with” here?

Yes. After a person, と often means “with” in the sense of “together with”:

友達とピザを食べる – eat pizza with (my) friend(s)
家族と住んでいます – I live with my family

So 友達と in this sentence means “with (my) friends.”
Note that と can also mean “and” when listing nouns (e.g., 猫と犬 = cats and dogs), but here it clearly means together with.

Why is ピザ marked with を and also ゲーム marked with を? Can you have two を in one sentence?

Yes, you can have multiple を in one sentence if they belong to different verbs.

Here:

ピザを食べながら
- ピザ is the direct object of 食べる (to eat)
ゲームをしました
- ゲーム is the direct object of する (to do / to play)

The structure is:

(ピザを食べながら) ＋ (ゲームをしました)

Two separate verb phrases, each with its own を. That’s completely normal.

How does 食べながら work? Why is it 食べ and not 食べて?

ながら attaches to the ます-stem of a verb to mean “while doing (that).”

Dictionary form: 食べる
ます-stem: 食べ
食べ + ながら → 食べながら = “while eating”

Pattern:

[verb ます-stem] + ながら = “while (simultaneously) doing [verb]”

Examples:

音楽を聞きながら勉強する – study while listening to music
テレビを見ながらご飯を食べる – eat while watching TV

食べて is from the て-form and has different uses (connecting actions in sequence, giving reasons, etc.). For “while doing X,” you specifically need ます-stem + ながら.

Does ながら mean the two actions happen at the same time, or one after the other?

ながら expresses simultaneous or overlapping actions, not a sequence.

In this sentence:

ピザを食べながらゲームをしました
→ “(I) played games while eating pizza.”

The main action is usually the verb after ながら:

Focus: ゲームをしました (played games)
Background / accompanying action: ピザを食べながら (while eating pizza)

If you wanted sequence (first eat, then play), you’d normally use something like:

ピザを食べてからゲームをしました。 – After eating pizza, (I) played games.

Could I also say ゲームをしながらピザを食べました? Does that change the meaning?

Yes, that is grammatically fine, and it slightly shifts the focus.

ピザを食べながらゲームをしました。
→ Focus is more on playing games; eating pizza is secondary.
ゲームをしながらピザを食べました。
→ Focus is more on eating pizza; playing games is the background action.

In everyday conversation, the difference is subtle; both can describe the same situation. The verb after ながら gets the main emphasis.

Why is it ゲームをしました and not just ゲームしました or あそびました?

ゲームをする is the standard way to say “to play (video) games / games.”
- ゲームをしました = “played games” (polite past)
ゲームしました (dropping the を) is common in casual speech, but ゲームをしました is more textbook-correct and clearly polite.
あそぶ means “to play / hang out / have fun” more generally.
- 友達とあそびました = “I hung out / played with my friends.”
- It doesn’t specifically say you played games, though context could imply it.

So ゲームをしました clearly says “(I) played games,” which matches the idea of playing video/board games while eating pizza.

Who is the subject in this sentence? Where is “I” or “we”?

Japanese often omits the subject when it is clear from context.

In this sentence there is no word for “I” or “we”:

No 私（わたし）, 僕（ぼく）, 俺（おれ）, etc.

But in natural Japanese, if you’re talking about your own experience, it’s understood as:

“(I / we) did [this] on Friday night.”

If you wanted to make it explicit, you could say:

金曜の夜に私は友達とピザを食べながらゲームをしました。
金曜の夜に友達とピザを食べながらゲームをしました。 (subject omitted; still “I” in context)

Both are grammatically correct; the second is more natural in casual storytelling.

Is the politeness level consistent? しました is polite, but the rest looks like dictionary forms.

Yes, it’s consistent and natural.

Polite past is marked by:

～ました on the main verb: しました

The other verbs appear only as stems or in non-final positions:

食べながら uses the ます-stem 食べ (same form as in 食べます), so it fits with polite speech.
Only the final verb in a sentence has to show the politeness level; embedded or connecting forms (like 食べながら) do not take ます or ました themselves.

So ピザを食べながらゲームをしました is a fully polite sentence.