"I'm easy" is a casual phrase that is often used to imply that one is flexible and adaptable. There are several synonyms for this phrase, including "I'm flexible," "I'm open-minded," "I'm laid-back," "I'm chill," and "I'm relaxed." These phrases convey a similar sentiment and can be used interchangeably depending on the context. Additionally, the phrase "I'm down for anything" can also be used to express a similar attitude of flexibility and willingness to go with the flow. Overall, these synonyms portray a sense of easy-goingness and an openness to new experiences, which can be positive traits in a variety of situations.