eyes are out on stalks
US /aɪz ɑr aʊt ɑn stɔks/
UK /aɪz ɑr aʊt ɑn stɔks/

1.
目が飛び出しそうになる, 非常に驚く
to be extremely surprised or shocked, often with one's eyes wide open
:
•
When she saw the huge diamond ring, her eyes were out on stalks.
巨大なダイヤモンドの指輪を見たとき、彼女の目は飛び出しそうだった。
•
The children's eyes were out on stalks when they saw all the presents under the tree.
木の下のすべてのプレゼントを見たとき、子供たちの目は飛び出しそうだった。