"Get in on" is a phrasal verb that means to become part of something, often an opportunity or a conversation. There are several synonyms that can be used for this phrase, including "join in," "take part," "get involved," and "participate." These synonyms all suggest actively engaging in an activity or conversation rather than merely observing or commenting on it. Other synonyms that could be used include "enter into," "be part of," and "contribute to." The choice of synonym will depend on the context of the sentence and the tone that the writer wishes to convey. Regardless of which synonym is used, all suggest a sense of immersion and engagement in the situation.