Texting While Intoxicated. A newer version of drunk dialing. TWI is the phenomenon that happens when your inhibitions are lowered by the use of alcohol and you boldly send a text to someone who, if sober, you otherwise would not have.
You receive a text past midnight from an ex that says, "You are still the hottest person I know." Your current partner reads it and says, "Well your ex just got another TWI."