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."
Typing while intoxicated. Usually leading to instant messaging/emailing people who you normally don't talk to, but it seems like a good idea at the time.
Joe: Hey mike, remeber that chick Lauren we met at the bar a month ago
Mike: The one with the nice money makers?
Joe: Ya, i TWIed last night to her, and she thinks im a creep now.