have someone by the balls
US /hæv ˈsʌmˌwʌn baɪ ðə bɔlz/
UK /hæv ˈsʌmˌwʌn baɪ ðə bɔlz/

1.
avere qualcuno in pugno, controllare completamente qualcuno
(vulgar slang) to have complete control over someone, especially by having information that could harm them
:
•
The prosecutor really had him by the balls with all the evidence.
Il procuratore lo aveva in pugno con tutte le prove.
•
If you owe them money, they'll have you by the balls.
Se gli devi dei soldi, ti avranno in pugno.