someone's back is turned
US /ˈsʌm.wʌnz bæk ɪz tɜrnd/
UK /ˈsʌm.wʌnz bæk ɪz tɜrnd/

1.
누군가의 등이 돌려져 있을 때, 누군가가 주의를 기울이지 않을 때
when someone is not looking or paying attention
:
•
The children started playing pranks as soon as their mother's back was turned.
엄마가 등을 돌리자마자 아이들은 장난을 치기 시작했다.
•
He always tries to sneak a cookie when my back is turned.
내가 등을 돌리면 그는 항상 몰래 쿠키를 훔치려 해.