The phrase "have relations with someone" can be replaced with various synonyms that convey similar meanings. Some of the most commonly used alternatives include: have sex with, sleep with, intimate with, fornicate with, copulate with, mate with, lay with, hook up with, make love with, and be intimate with. Each of these synonyms has a slightly different connotation and level of formality, making it important to choose the one that best suits the context of the situation. Regardless of which synonym is used, it is important to always prioritize consensual and respectful interactions with others.