The phrase "sticking in" can have a few different meanings, so there are a variety of synonyms that could apply depending on the specific context. If "sticking in" refers to an object remaining lodged or wedged somewhere, synonyms could include jammed, embedded, lodged, trapped, or ensnared. If it refers to a thought or idea lingering in one's mind, possible synonyms might include persisting, recurring, haunting, or lingering. Finally, if "sticking in" is meant in the sense of someone or something attracting or drawing attention, possible synonyms could include capturing, commanding, captivating, holding, or intriguing.