He's like a fiend in my pocket, always causing trouble.
Он словно карманный демон, постоянно причиняющий неприятности.
Definitions
The phrase 'fiend in (someone's) pocket' refers to a harmful or destructive influence that someone carries with them, often secretly. It can describe an addiction, vice, or negative habit that is always present and has a detrimental effect on the person's life.
