put a bug one's ear (verb) forewarn: caution that something may happen
Sinonime: admonish,
advise,
alarm,
alert,
apprise,
dissuade,
flag, forbode, give fair warning, give the high sign,
portend, premonish, pull one's coat, put a bug in one's ear, put on guard, put one wise, telegraph,
tip, tip off, wave a red flag