When we talk about "slip out of", we usually use it to describe something or someone that has managed to escape or disappear from a place or situation. If you're looking for synonyms that can replace this phrase, you may consider using "slip away", "sneak out", "skedaddle", "vanish", or "abscond". These words can add more color and nuance to your writing by conveying different emotions and ideas. For instance, "sneak out" emphasizes the sneakiness and secrecy of the escape, while "skedaddle" implies a sense of urgency and haste. Whatever word you choose, make sure it fits the context and tone of your writing.