"Butting in" is a phrase that refers to someone interrupting or intruding in a conversation or situation without being invited or welcomed. There are several synonyms for this phrase that, depending on the context, can be used interchangeably. Some common alternatives include "interfering," "interrupting," "meddling," "intruding," "butting into," and "butting in on." Each of these words suggests an unwelcome intrusion or interruption, and they convey a sense of annoyance or frustration with the person who is doing the butting in. Whether you choose to use "butting in" or one of its synonyms, be sure to use it appropriately and with the right tone to convey your message effectively to your audience.