Learn Croatian: Ići ću po šampon i novu spužvu. - I will go get the shampoo and a new sponge.

In Croatian, when you are going somewhere specifically to fetch, pick up, or get something, you use a verb of motion (like ići, meaning to go) followed by the preposition po. You don't need a separate verb for "to get"; the preposition handles that meaning entirely when paired with motion.

What case does po trigger here, and why does šampon not seem to change its ending?

When used to mean "to fetch," po requires the accusative case. You can see this clearly with the feminine noun spužva (sponge), which becomes spužvu, and its adjective nova, which becomes novu. However, šampon is a masculine inanimate noun. In the accusative case, masculine inanimate nouns look identical to their nominative (dictionary) form, which is why it doesn't change.

Why is it written as Ići ću without dropping the final 'i' from the verb?

Normally, when forming the future tense by putting the auxiliary clitic (ću, ćeš, etc.) directly after the verb, verbs ending in -ti drop their final 'i' in writing (for example, raditi becomes radit ću). However, verbs that end in -ći, such as ići, are an exception to this spelling rule. They keep their full infinitive form, so it is written as ići ću.

Could I just say ?