Japanese with Manga
Learning through examples in manga

Contracting 〜る＋な to 〜んな

Grammar: Colloquial and Casual Speech

A verb ending in 〜る followed by the particle な may contract as 〜んな.

Examples

Don't worry with すんな

Manga panel from 俺物語!! showing example of Contracting 〜る＋な to 〜んな.
俺物語!! » Volume 6 » Page 56

Takeo takes his pregnant mother to the hospital, as she’s getting close to delivery. Once there, she gives Takeo and his friend Suna a list of things to take care of during her stay.

母(かあ)さん:
「大丈夫(だいじょうぶ)から心配(しんぱい)すんな」
“I'll be fine, so don't worry.”