have butterflies in your stomachhave butterflies (in your stomach)
to feel very nervous, usually about something you are going to do.
She had butterflies in her stomach as she walked out onto the stage.
have butterflies in (one's) stomach
To have a feeling of nervousness, often before a performance or undertaking of some kind. I almost didn't go on stage and perform tonight because I had butterflies in my stomach.
have butterflies in your stomach
have a queasy feeling because you are nervous. informal