put a bee in someone’s bonnet—give a person a compulsive idea that may seem excentric or odd:
- Mayoral candidate Marcic says his campaign has “put a bee in his bonnet” about public drinking and it is an issue he will pursue.
put a bug in someone’s ear—(also: put a flea in someone’s ear) give a person a hint or advice about smth.:
- I tried to put a bug in his ear about making his next film about bike touring, but I’m not sure how successful I was.
Cf..: get the bug —(sl.) develop a strong interest or enthusiasm for a particular activity:
- Once you start learning about computers, you get the bug and spend more and more time with them.