The best thing about old AOL -- which is to say, the best thing about the mid-1990s -- was unsend. If you sent an e-mail to another AOL user, up until the moment that person actually opened it, you had the option of taking it all back. It was like it never happened! Gmail has a lot of optional features that let you create impediments to hasty e-mailing, but in the end, it won't retrieve your message from the recipient's inbox.
Fun fact: Twitter will.
Maybe you were angry, maybe you were love sick, maybe you were drunk. No matter the reason, we all know the horrible feeling of waking up in the morning and realizing that you actually did send that message. If it was a text or an e-mail, I'm sorry to say, there's nothing you can do; but if it was a DM on Twitter, the answer is simple: just delete it.
When you delete a DM, Twitter removes it not only from your outbox but also from the recipient's inbox.
Here's how to delete a DM on the Web:
Click on the gear icon.
Select Direct Messages.
Find the offending DM.
Click on the trash can.
Word of caution: If your boss/estranged romantic partner has certain notifications turned on, then they may get the message another way. Users can receive e-mail, texts, or push notifications for incoming messages that include the message itself. But, here's the thing: maybe the recipients don't have that turned on. Even if they do, maybe they don't actually read any of the dozens of e-mails Twitter sends a day. There's no guarantees in life, but I offer you hope.
Additionally, in one way Twitter's unsend is actually an improvement over old AOL's. Even if the recipient has read it, even if she's responded to it, you can still delete it. Snapchat and Facebook's Poke exist specifically to provide people with a way of sending self-destructing messages. You can't automate it, but at any time you can tell a Twitter DM to self-destruct...and not just the ones you've sent.
Fun fact No. 2: When you delete a DM that you have received, Twitter removes it from the sender's outbox.
Think about that for a second. If you get a message that you don't, for whatever reason, want to respond to, don't leave it hanging there, just delete it. It never happened. There is no proof within that person's reach that the message ever existed.
Yes, of course this could drive someone absolutely insane, but it could also be used for good! Just like we've all sent messages we regret, so, too, have we all received messages that someone else regrets.
So the next time you receive a DM that is stained in tears or spittle or gin, remember that if you want to, you could make the sender's day: just delete it.