A conversation between the two:

Mystia: 「だからもうﾀﾝﾄﾞﾘｰﾁｷﾝは無いんですよ～」
Yuyuko: 「えぇー、じゃあなんこつで良いわぁ、おつまみ～かぷっ」　こりこり
Mystia: 「ひゃうっ！？」

Mystia: "I told you, there's no more Tandoori chicken left."
Yuyuko: "Aww, then cartilage will be fine as a snack. Gulp" Chew, chew
Mystia: "Hyau!?"

I made a guess on かぷっ as a gulping sfx.

So she's just bitting her ear, or eating it?