The phrase "puts a bug in one's ear" is commonly used to refer to someone suggesting an idea or planting a thought in someone's mind. There are several synonyms for this phrase, including "planting a seed," "planting an idea," "putting the idea in someone's head," "instilling a thought," and "implanting a notion." These phrases are used interchangeably in conversation, and all imply the act of introducing an idea into someone's mind. When someone "puts a bug in your ear," they may be trying to influence your thoughts or encourage you to consider a new perspective or action.