Learn Hardcore Turkish: Teslim fişini sakladım, kargocu da bana dostça teşekkür etti. - I kept the delivery slip, and the courier thanked me in a friendly way.

Here da is the additive clitic meaning also / too: kargocu da = the courier also. It’s written separately and follows vowel harmony (front/back): de/da, but it never becomes te/ta.

Additive clitic: Ben de geliyorum (I’m coming too).
Not to be confused with the locative case suffix -de/-da/-te/-ta: evde (at home), which is attached to the word and can be te/ta after a voiceless consonant.

Why is it bana and not beni after teşekkür etti?

Because teşekkür etmek selects the dative case for the person thanked: X’e/Y’ye teşekkür etmek = to thank X/Y.

Bana teşekkür etti = He/She thanked me (correct).
Beni teşekkür etti is ungrammatical.
Compare: verbs that take the accusative: Beni gördü (He/She saw me).

Does teslim fişini mean “his/her receipt”? What is that -ni?

No. Teslim fişi is an indefinite noun compound (belirtisiz ad tamlaması): the head noun takes a 3rd person possessive marker as a compound marker, not actual possession. When you add the accusative to that head, you get -nı/-ni/-nu/-nü.

Breakdown: teslim fiş-i-n-i
- fiş-i: 3rd person possessive on the head (compound marker)
- -n-: buffer consonant
- -i: accusative case
Parallels: okul kapısı → okul kapısını; kargo takip numarası → kargo takip numarasını.

Why does the object have the accusative here?

Because it’s a specific, definite object: the delivery receipt. In Turkish, definite direct objects take the accusative; indefinite ones don’t.

Definite: Teslim fişini sakladım (I kept the delivery receipt).
Indefinite: Bir teslim fişi sakladım (I kept a delivery receipt) or bare Teslim fişi sakladım (sounds like “some delivery receipt(s)” and is less natural here).

What nuance does sakladım have? Is it “hid” or “kept”?

Saklamak can mean:

to put away/keep for safekeeping (neutral/common here),
to hide (context can give this sense).

Alternatives:

gizlemek = to conceal/hide (more secretive),
korumak = to protect,
tutmak = to hold/keep (general).

How are the verbs built morphologically: sakladım, teşekkür etti?

sakla-dı-m: root sakla- (keep/store) + past -dı (harmonizes to -dı/-di/-du/-dü) + -m (1st sg).
teşekkür et-ti: light-verb construction teşekkür etmek (to thank) + past -ti; with etmek, the t doubles: etti.

What does the placement of da tell us about emphasis? Could I say bana da instead?

Yes, da attaches to the word it emphasizes.

Kargocu da bana teşekkür etti: The courier also thanked me (someone else did something similar, or another person thanked me earlier; the “also” is about the courier).
Kargocu bana da teşekkür etti: The courier thanked me, too (in addition to thanking someone else).
Bana kargocu da teşekkür etti: Focus on me first; “the courier also thanked me.” Word order shifts focus.

Where is the subject in the first clause?

It’s implied: (Ben) teslim fişini sakladım. Turkish is pro-drop; the -m on sakladım already encodes I. In the second clause, kargocu is the overt subject.

Why a comma instead of ve? Could I use ve?

The comma separates two coordinated clauses. You could say Teslim fişini sakladım ve kargocu da bana dostça teşekkür etti. Using da already conveys the additive sense; ve is optional and slightly more formal/explicit.

What does dostça mean morphologically?

It’s dost (friend) + adverbial/derivational suffix -ça/-çe, meaning “in a friendly way; friendly-like.”

Examples: yavaşça (gently), Türkçe (Turkish, as a language).
Synonyms in context: dostane, samimi bir şekilde, güler yüzle.

Is kargocu the usual word for “delivery person”? Any alternatives?

Kargocu is common and colloquial (courier/delivery person from a shipping company). Alternatives:

kurye (courier; common, esp. for motorcycle/bicycle couriers),
kargo görevlisi (more formal/neutral),
dağıtıcı (distributor/deliverer; context-dependent),
postacı (mail carrier; for postal service).

Any pronunciation tips for tricky sounds here?

kargocu: c is like English j in “job” ([dʒ]); stress usually near the end: kar-go-cu.
teşekkür: ş = “sh”; double kk is geminate; stress on the last syllable: te-şek-kür.
sakladım: ı is the close back unrounded vowel (no exact English equivalent), roughly like the second syllable in “roses” for some speakers: sak-la-dım.
fişini: ş = “sh”; front vowels i/ü/ö keep the word sounding “light.”

Could I drop dostça? Does it change the meaning much?

Yes, you can say Kargocu bana teşekkür etti. Dostça adds the manner (“in a friendly way”). Other adverbs of manner you might use: içtenlikle, güler yüzle, nazikçe.

When do I choose de vs da for the additive clitic?

Pick de after a front vowel (e, i, ö, ü) and da after a back vowel (a, ı, o, u):

Öğretmen de geldi (front vowel → de).
Kargocu da geldi (back vowel → da).

Remember: this clitic is written separately and never becomes te/ta.

What’s that extra -n- in fişini?

It’s a buffer consonant (kaynaştırma ünsüzü) used when a vowel-initial suffix follows a vowel-final form. Here, the head already has the possessive -i (compound marker), and then the accusative -i is added, so -n- keeps the vowels apart:

fiş-i-n-i, kapı-s-ı-n-ı (the buffer can be y/s/ş/n depending on context).