"Subtweeting" is the practice of tweeting about someone without sending them a notification about your tweet by mentioning their Twitter handle. Sometimes, this also means not even mentioning the person you're tweeting about by name but leaving readers to work out from context clues who it is you might be talking about. Usually this is passive-aggressive behavior intended that allows a Twitter user to speak negatively about another Twitter user without specifically mentioning them. But sometimes it's a tactic used by college football coaches to send public messages to players without running afoul of NCAA rules. According to the Texas A&M compliance office, it's now impermissible to subtweet recruits under certain circumstances.