Learn Hardcore Turkish: Müşteri hesabını öderken bahşiş bırakmayı unutmamalı. - The customer should not forget to leave a tip when paying the bill.

öderken means “while paying.” It comes from the verb ödemek (“to pay”). You take the stem öde-, add the present/future tense marker -r (giving öder), and then attach -ken, which creates the meaning “while doing X.”

Why is hesabını in the accusative case, and what does the -nı ending indicate?

Hesabını breaks down as hesap (“bill” or “check”) + the third-person singular possessive suffix -ı (“his/her bill”) + the accusative case marker -nı (because hesab-ı is definite). Here it means “the customer’s bill,” marked as the direct object of öderken.

What is bahşiş?

Bahşiş simply means “tip,” the extra money you leave for good service. It’s a standalone noun and remains uninflected here because it’s not marked by case or possession.

Why is it bırakmayı instead of bırakmak?

With verbs like unutmak (“to forget”), the action you might forget is expressed as a verbal noun in the accusative. You take the infinitive bırakmak (“to leave”), change -mak to -mayı (infinitive + accusative), and get bırakmayı: “the act of leaving (a tip).”

How is unutmamalı formed, and what does it express?

Unutmamalı expresses a necessity or strong recommendation (“one should not forget”). It’s built as unut- (root “forget”) + -ma (negation) + -malı (necessity). Together they make unutmamalı, literally “must not forget” or “should not forget.”

Why is there no “you” or “they” in the sentence, and why is the verb in third person?

Turkish often drops personal pronouns when context makes them clear. Here unutmamalı is in third person singular, giving a general or impersonal recommendation: “One should not forget to leave a tip.” It’s like English “You shouldn’t forget to tip,” but phrased more universally.

How would you say this directly to a customer, in a polite form?

To address the customer with “you,” you could use the second-person plural imperative or advice form:
Hesabınızı öderken bahşiş bırakmayı unutmayın.
Here hesabınızı is “your bill,” and unutmayın is the polite “don’t forget.”

Can you replace öderken with ödemeden önce, and what’s the nuance?

Yes. Ödemeden önce means “before paying.” So
Müşteri hesabını ödemeden önce bahşiş bırakmayı unutmamalı.
This shifts the focus slightly: “One should not forget to leave a tip before paying the bill,” rather than “while paying.” Both are correct; öderken emphasizes simultaneous action.