Learn Hardcore Indonesian: Kebetulan saya bertemu tetangga di toko.

It signals the meeting happened by chance, like by coincidence or as it happens. Without it, Saya bertemu tetangga di toko is neutral (could be planned or accidental). With Kebetulan, you’re telling the listener it wasn’t arranged.

Where can I place kebetulan? Is the current position the only option?

You can also say Saya kebetulan bertemu tetangga di toko. Both are natural. Putting it at the very end (… di toko kebetulan) sounds odd. You can also front the place/time for emphasis: Di toko, kebetulan saya bertemu tetangga.

Do I need dengan after bertemu?

No. Both bertemu tetangga and bertemu dengan tetangga are correct. Adding dengan can sound a bit more formal or careful. In everyday speech, many drop it.

Does tetangga mean my neighbor, a neighbor, or the neighbor?

Indonesian has no articles, so tetangga is unspecified by default and usually understood as someone who is your neighbor from context. To be explicit:

My neighbor: tetangga saya
A neighbor: seorang tetangga
The neighbor (previously known/specific): tetangga itu

Is tetangga singular or plural here?

Number is unspecified. If you need plural, use:

para tetangga (a group of neighbors, formal)
tetangga-tetangga (reduplication)
beberapa tetangga (some neighbors)

What exactly does di toko mean? At the store or in the store?

di marks a static location, so it can be either at or in depending on context. To express motion toward the store, use ke: ke toko (to the store). Example: Saya di toko = I am at/in the store; Saya ke toko = I’m going to the store.

Does this sentence imply past tense?

Indonesian doesn’t mark tense. Saya bertemu… can be past, present, or even future depending on context. Add time words to clarify:

tadi (earlier today): Tadi saya bertemu…
kemarin (yesterday)
barusan (just now)

How would I say it more casually?

Use informal pronouns and the colloquial verb:

Tadi aku ketemu tetangga di toko.
Jakarta slang: Gue ketemu tetangga di toko tadi. You can also use sama instead of dengan: ketemu sama tetangga.

What’s the difference between bertemu, ketemu, menemui, and berjumpa?

bertemu: neutral, to meet (often accidental or neutral).
ketemu: colloquial for bertemu.
menemui: to go meet/visit someone intentionally (transitive). Example: Saya menemui tetangga = I went to meet/see my neighbor.
berjumpa: more formal/literary; similar to bertemu. Related: ketemuan = to arrange to meet (each other); papasan = to bump into while passing.

Is kebetulan always neutral, or can it mean luckily?

It’s often neutral (by chance), but in everyday talk it can imply convenience or luck depending on tone and context. For clearly lucky, add untung/syukurlah; for clearly unfortunate, use sayangnya. Example: Kebetulan saya bawa uang tunai can feel like as it happens/luckily I had cash.

Do I need a word like “a” before tetangga or toko?

No. Indonesian doesn’t use articles. You can add classifiers if you want to emphasize singular:

seorang tetangga (a/one neighbor)
sebuah toko (a/one store) In your sentence, di toko is perfectly natural. di sebuah toko adds the sense of some particular store, unspecified which.

Can I front the place or time for emphasis?

Yes. Common options:

Di toko tadi, kebetulan saya bertemu tetangga.
Tadi di toko, saya bertemu tetangga. Fronting sets the scene and sounds natural.

Can I drop saya?

In informal conversation, yes, if context makes the subject obvious: Kebetulan ketemu tetangga di toko. In writing or when clarity matters, keep saya.

How do I say next-door neighbor?

Use tetangga sebelah (or tetangga sebelah rumah). Example: Kebetulan saya bertemu tetangga sebelah di toko.

Is pada toko okay instead of di toko?

No. Use di for locations. pada is used in more formal contexts for abstract relations, times, or with pronouns (e.g., pada hari Senin, pada mereka), not for physical places like toko.