Bewaar de smoes, voor het geval de jarige vroeg komt.

Yes. Bewaar is the imperative form of bewaren, meaning to keep, to save, or to hold on to.

Dutch imperatives often leave out the subject, just like English:

• Bewaar de smoes. = Keep the excuse.
• implied subject: you

So the sentence is giving an instruction or advice.

Een smoes means an excuse, often with the idea that it is not fully honest, or that it is a made-up explanation.

So it is usually closer to:

• excuse
• pretext
• cover story

It is not usually a neutral excuse like a valid reason. It often suggests something slightly suspicious or playful.

Because smoes is a de-word in Dutch: de smoes.

Dutch nouns have grammatical gender/common article classes, so you simply have to learn whether a noun takes de or het. There is not always a logical reason visible from the meaning alone.

Here:

• de smoes
• plural: de smozen

Voor het geval means in case.

It is a fixed expression in Dutch:

• voor het geval dat ...
• voor het geval ...

In everyday Dutch, dat is often omitted when the rest of the clause is clear.

So:

• voor het geval de jarige vroeg komt means
• in case the birthday person comes early

It introduces a possible situation you want to be prepared for.

Good question. Jarig means having a birthday or birthday-related.

From that adjective, Dutch can make a noun:

• de jarige = the person whose birthday it is
• in natural English: the birthday boy/girl, the birthday person, or simply the one celebrating their birthday

So de jarige is a very common Dutch way to refer to the person whose birthday is being celebrated.

Because de jarige vroeg komt is a subordinate clause introduced by voor het geval.

In Dutch subordinate clauses, the conjugated verb usually goes toward the end of the clause. That is why you get:

• de jarige vroeg komt

Compare:

Main clause:

• De jarige komt vroeg. = The birthday person comes early.

Subordinate clause:

• ... voor het geval de jarige vroeg komt. = ... in case the birthday person comes early.

So the changed word order is normal Dutch subordinate clause word order.

Because Dutch often uses the present tense for future meaning, just like English often does.

Compare:

• English: In case he comes early
• Dutch: voor het geval hij vroeg komt

Even though the event may happen later, the present tense is the normal choice here. Dutch does not need a separate future form in this sentence.

Here vroeg means early.

It is an adverb describing komt:

• vroeg komt = comes early

Be careful not to confuse it with the past tense of vragen:

• hij vroeg = he asked

In this sentence, the meaning is clearly early, because it describes the timing of arrival.

The comma is possible, especially if the writer wants a small pause or clearer separation:

• Bewaar de smoes, voor het geval de jarige vroeg komt.

In many cases, Dutch writers might also write it without a comma:

• Bewaar de smoes voor het geval de jarige vroeg komt.

So the comma is not the main grammar point here. It is more about style, rhythm, and clarity than a big meaning difference.

Yes, depending on context. Bewaren can mean:

• keep
• save
• store
• put aside

In this sentence, keep is probably the most natural English choice:

• Keep the excuse, in case the birthday person comes early.

The idea is: do not use the excuse yet; hold on to it in case you need it.

Yes. You could also say:

• Bewaar de smoes voor het geval dat de jarige vroeg komt.

That is grammatically fine. In modern everyday Dutch, people very often leave out dat, so:

• voor het geval de jarige vroeg komt sounds completely normal and natural.

Both versions are correct.