No time to leisurely eat with 呑気

Vocabulary Explanation: Carefree with 呑気

After an enemy attack changes Usagi and Mamoru into kids, Usagi wakes to find the two of them living together as a couple. As Usagi wanders into the dining room, Mamoru is placing a plate of french toast on the table. He greets her and asks Usagi what type of jam she wants on her toast. Usagi responds, then realizes she needs to get to school.

うさぎ:: 「あたし　ライムのマーマレードッ」; “I'll have lime marmalade!”; 「ってそんな呑気(のんき)に食(た)べてるヒマなんかあたしにはっっ」; “Ah, I don't have any time to be leisurely eating!”; Literal: “Wait, I don't have time to be eating so carefree!!”

Key Points

1呑気(のんき)に describes the manner

The に turns 呑気(のんき) into an adverb, so it describes how she would be eating.
In this scene it means eating in a relaxed, unconcerned way despite needing to get to school.

2食べてる is casual 食べている

食(た)べてる drops the い from 食(た)べている, a common spoken contraction.
The phrase is not about one bite; it pictures spending time sitting there eating.

3ヒマなんかあたしには rejects the idea strongly

なんか downplays free time as something she absolutely does not have.
The order puts あたしには late, emphasizing that for Usagi there is no time for this.