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

1.
o coração na boca, sentir-se muito nervoso
to feel very nervous or frightened
:
•
When the roller coaster started, my heart was in my mouth.
Quando a montanha-russa começou, meu coração estava na boca.
•
Her heart was in her mouth as she waited for the exam results.
O coração dela estava na boca enquanto esperava pelos resultados do exame.