The phrase "sneaked in" refers to entering a room or building without being noticed or detected. Some synonyms for this phrase include "slipped in," "crept in," "snuck in," "quietly entered," and "furtively made an entrance." These words all convey the idea of entering a place without drawing attention to oneself or causing a disturbance. Other possible synonyms could include "snaked in," "slid in," "sneaked through the back door," or "slunk in unnoticed." No matter which synonym is chosen, the overall idea is that the person entered the room or building inconspicuously and without drawing attention to themselves.