The phrase "butt in" is commonly used to refer to someone who interrupts or interferes in a conversation or situation they are not invited to or involved with. There are several synonyms for "butt in" that can be used interchangeably in different contexts. Some of these include "interrupt," "interfere," "intrude," "meddle," "interject," "butt into," "barge in," "cut in," "crash," "hijack," and "overstep." Each of these words can be used to describe someone who is behaving in an assertive or pushy manner, often causing frustration or annoyance to those around them. Whether it's in a social or professional setting, it's important to be mindful of our actions and respectful of others' boundaries and space.