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

1.
tener a alguien agarrado por los huevos, tener a alguien bajo control
(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.
El fiscal lo tenía agarrado por los huevos con todas las pruebas.
•
If you owe them money, they'll have you by the balls.
Si les debes dinero, te tendrán agarrado por los huevos.