Learn Hardcore Turkish: İster parkta ister kafede çay içelim. - Let's drink tea either in the park or at the cafe.

It presents two alternatives (either ... or / whether ... or) and says the main suggestion holds in either case. It often implies indifference: both options are equally fine.

Is ister here the verb istemek?

Historically yes—it’s the 3rd-person aorist of istemek. But in the fixed correlative ister ... ister ..., it acts like a conjunction and doesn’t mean wants.

Do I have to repeat ister before each option?

Yes. Standard Turkish repeats it: İster parkta ister kafede ... Dropping the second ister is not idiomatic. You can add olsun for emphasis: İster parkta olsun ister kafede, ...

Why is it parkta but kafede? What suffix is this?

It’s the locative suffix -DA (in/at/on), shaped by harmony and voicing:

park + -DA → parkta (final k is voiceless → t; back vowel a → a)
kafe + -DA → kafede (ends in a vowel → d; front vowel e → e)

Could I say parka or kafeye instead?

Those are dative -A (to/toward): parka, kafeye. Use locative -DA here because the action happens in the place, not motion toward it.

Why is çay bare (no -ı/-i)?

Indefinite direct objects are unmarked in Turkish. çay içelim = let’s drink (some) tea. If you mean specific tea already known, use accusative: çayı içelim = let’s drink the tea.

What exactly does içelim express, and how is it built?

It’s 1st person plural imperative/optative: let’s drink. Morphology:

iç- (drink)
-e- (optative vowel by harmony)
-lim (1pl) By harmony you’ll also see -alım/-elim across verbs: yapalım, gidelim.

How is içelim different from içeriz, içeceğiz, or içelim mi?

içelim: suggestion/invitation (let’s drink).
içeriz: aorist/habitual or neutral prediction (we drink / we’d drink).
içeceğiz: future (we will drink).
içelim mi?: polite suggestion (shall we drink?).

Can I move parts around? Where can ister ... ister ... go?

Yes, it can be fronted or placed after the object:

İster parkta ister kafede çay içelim. (original)
Çay ister parkta ister kafede içelim. (object first) Keep çay içelim together near the end; İçelim çay or splitting the chunk sounds odd in this register.

Should there be a comma after the ister ... ister ... part?

Optional. Many write İster parkta ister kafede, çay içelim. Without a comma is also fine in a short sentence like this.

Can I use ya ... ya ..., ya da, or veya instead?

Ya ... ya ... = either ... or: Ya parkta ya kafede çay içelim. More colloquial, often felt more exclusive.
ya da / veya = or: Parkta ya da kafede çay içelim.
İster ... ister ... is a bit more formal/rhetorical and pairs nicely with suggestions/wishes.

How do I make it negative?

Insert the negative before the optative ending:

Çay içmeyelim. (let’s not drink tea)
With alternatives: İster parkta ister kafede çay içmeyelim.

Can I add bir before çay?

Yes. Bir çay içelim is natural and often implies “let’s have a tea (each).” Without bir, it’s generic “some tea.”

Is de in kafede the same as the separate de/da meaning “also/too”?

No. In kafede, -de is the attached locative suffix. The clitic de/da (“also/too”) is written separately: kafede de = “also at the café.”

Any difference between kafede and kahvede?

Yes:

kafe → kafede: a modern café.
kahve → kahvede: often “at the (traditional) coffeehouse” (or literally “in the coffee,” depending on context). They evoke different vibes; both are grammatically fine here.

Do I need to say biz?

No. The ending -lim already encodes “we.” Biz çay içelim is only used for emphasis or contrast.