someone's heart is in their mouth

US /ˈsʌm.wʌnz hɑːrt ɪz ɪn ðer maʊθ/
UK /ˈsʌm.wʌnz hɑːrt ɪz ɪn ðer maʊθ/
"someone's heart is in their mouth" picture
1.

tener el corazón en la boca, sentirse muy asustado

to feel very nervous or frightened

:
When the roller coaster started, my heart was in my mouth.
Cuando la montaña rusa arrancó, se me puso el corazón en la boca.
Her heart was in her mouth as she waited for the exam results.
Se le puso el corazón en la boca mientras esperaba los resultados del examen.