The phrase "puts a bug in one ear" means to suggest an idea or concept to someone in a persistent way. Synonyms for this phrase include "plants a seed," "plants an idea," or "drops a hint." Other phrases that convey the same meaning include "leads on," "coaxes," or "nudges." Additionally, one may "whisper sweet nothings," "sway," or "persuade" someone to see things from a new perspective. When trying to influence someone's viewpoint, it's important to use tact and finesse. By doing so, you can successfully plant a thought in someone's mind without coming across as manipulative or overbearing.