This word means whore or fuck.
He uses this word the most, since it's from his language
They use a variation of the world known as "Kurva". You don't see it a lot because neither of them appear in a lot of comics.
Perhaps the most infamous, Croatia hates kebab not because he wants to follow brother Serbiaball, but the Arabs call him "Kurwa-tia". He gets quite agitated when called so.
He uses a variation of the word known as "curvă" (IPA: /kurvə/), which also means whore.
Serbia uses the word "Kurva".This word means prostitute in the Serbian slav language.
Russia uses the word "Kурва".
She uses a variation of the word known as "Ssibal", as this word means "fuck".
Surprisingly, the US hasn't censored this word as much on TV. Maybe because Polandball wants to remove homosex?