Tolong simpan boarding pass di saku jaket supaya tidak tertinggal saat check-in.

Tolong is a very common way to make a request politely in Indonesian. In this sentence, it works like please in English.

• Tolong simpan ... = Please keep/store ...
• It is softer and more polite than just saying Simpan ...

So tolong helps turn the sentence into a polite instruction.

Indonesian verbs often appear in a basic form without changing for the subject.

So:

• saya simpan = I keep
• Anda simpan = you keep
• dia simpan = he/she keeps

The verb itself does not change like English keep / keeps / kept. In this sentence, simpan is the base verb meaning keep, store, or put away safely.

Because this is a request after tolong, the base form is very natural:

• Tolong simpan ... = Please keep ...

Indonesian often leaves out the subject when it is obvious from context.

In a polite instruction like this, the listener is clearly the person being addressed, so you does not need to be stated.

A fuller version could be:

• Tolong Anda simpan boarding pass di saku jaket ...

But that sounds less natural in many everyday situations. Indonesian usually prefers the shorter version.

Here, di is a preposition meaning in, at, or on, depending on context.

• di saku jaket = in the jacket pocket

It shows location, not movement.

Compare:

• di saku jaket = in the jacket pocket
• ke saku jaket would suggest movement to the jacket pocket, but that is not the natural choice here

So simpan ... di saku jaket means keep it in the jacket pocket.

In Indonesian, the noun being described usually comes first, and the describing noun comes after it.

So:

• saku jaket = jacket pocket
• literally: pocket of jacket

This is a very common pattern:

• pintu mobil = car door
• kunci rumah = house key
• uang sekolah = school money/tuition money, depending on context

So saku jaket is the normal Indonesian order.

Yes. Indonesian often borrows words from English, especially in travel, technology, business, and airport contexts.

So boarding pass is very natural and widely understood. Some speakers may also say other variants, but boarding pass is common in real usage.

The same thing happens with:

• check-in
• email
• internet
• scan

Indonesian frequently mixes borrowed English words into otherwise Indonesian sentences.

Supaya means so that, in order that, or so.

It introduces the purpose or intended result of the first action.

In this sentence:

• Tolong simpan boarding pass di saku jaket = Please keep the boarding pass in your jacket pocket
• supaya tidak tertinggal = so that it does not get left behind

So supaya connects the action with its purpose.

A similar word is agar. In many contexts, supaya and agar are interchangeable:

• supaya tidak tertinggal
• agar tidak tertinggal

Both are natural.

Tertinggal means something like left behind, forgotten, or not taken along.

It comes from tinggal, which has meanings related to stay, remain, or be left. With the prefix ter-, it often describes a state or something that happened unintentionally.

So tidak tertinggal here means:

• not be left behind
• not accidentally get forgotten somewhere

This is more natural than a literal word-for-word English-style structure.

Because the focus is on the boarding pass being left behind, not on the person’s mental act of forgetting.

Compare:

• tidak lupa = not forget
• tidak tertinggal = not get left behind

In this airport context, tidak tertinggal is very suitable because it emphasizes the practical result: the boarding pass should not remain somewhere by accident.

The prefix ter- has several uses in Indonesian, but one common use is to show a state or an unintended event.

In tertinggal, it suggests something like:

• ended up left behind
• got left behind unintentionally

Other examples:

• terbuka = open / opened
• terjatuh = fell accidentally
• terlupa = forgotten

So tertinggal is not just stay behind in a neutral sense. It often carries the idea that something was unintentionally left somewhere.

Saat means when or during.

In this sentence:

• saat check-in = during check-in / when checking in

It marks the time when the problem might happen.

Other common time words include:

• ketika = when
• waktu = when / time
• saat = when / at the time of

Here, saat sounds natural and clear.

Because Indonesian often uses borrowed nouns or fixed expressions from English in a very flexible way.

So:

• saat check-in = during check-in / at check-in time

Even though English learners might expect a fuller form like saat melakukan check-in, Indonesian often leaves it short when the meaning is obvious.

A more expanded version could be:

• saat melakukan check-in

But saat check-in is more natural in everyday speech.

It is fairly neutral and polite.

Why?

• tolong makes it polite
• the structure is straightforward and natural
• borrowed terms like boarding pass and check-in are normal in modern everyday Indonesian

It would work well in spoken or written practical contexts, especially travel-related ones.

Yes, both ideas are basically the same here.

• di gives the location
• saku jaket means the jacket pocket

So the phrase naturally means:

• in the jacket pocket
• in a pocket of the jacket

Indonesian does not need an article like the or a, so context decides the exact English wording.

Indonesian does not use articles like the or a/an the way English does, and possession is often left unstated if it is obvious.

So:

• boarding pass does not need the
• saku jaket does not need your jacket pocket spelled out if the listener understands it

If needed, Indonesian can make possession explicit:

• di saku jaket Anda = in your jacket pocket

But in many real situations, the shorter version is completely natural.

Yes. Here are a few natural alternatives:

• Tolong simpan boarding pass di kantong jaket supaya tidak tertinggal saat check-in.
• Tolong taruh boarding pass di saku jaket agar tidak tertinggal saat check-in.
• Simpan boarding pass di saku jaket biar tidak tertinggal saat check-in.

A few notes:

• saku and kantong can both mean pocket, though usage can vary by context
• taruh means put
• biar is less formal than supaya or agar

So the original sentence is natural, but there are several acceptable variations.