Hello Shinhye! 'Ruin' is more serious than 'screw with someone.' To screw with someone is an informal phrase that means to create problems for them, or to lie to/joke with them. It's always used in informal situations and the meaning can be negative or neutral. It can be used with objects as well as people, and the meaning is similar. Negative examples: "I'm trying to concentrate on studying, but John keeps screwing with me." (John keeps distracting me.) "Don't screw with the radio, you'll break it." (If you continue touching the radio, you'll break it.) Neutral example: "I didn't mean what I said about your hair, I was just screwing with you." (What I said about your hair was a joke.) Let me know if you have any other questions! Best regards, Lee

It means to cheat, deceive, dupe, hustle people. But screw can have a number of other meanings too. A screw is just a metal object to fixate stuff. The verb screw without the preposition with but still followed by a pronoun indicating a person is a pejorative for having sex.