The expression "gat in to the act" means to become involved or to start taking part in something. There are several synonyms that can be used to convey a similar meaning. For instance, one could say "jump on the bandwagon," which means to join a popular trend or movement. Another option is to "get in on the action," which refers to joining in a situation that is already in progress. One can also use the phrase "throw one's hat into the ring," which denotes expressing interest in a contest or competition. Lastly, instead of "gat in to the act," one could use "take the plunge" or "dive in," both of which suggest taking a risk or daring move.