Hurrah for netsend :D
A few years back we had a normal Windows NT network about the office, which was every desktop with Windows NT and a Z number as an identifier for the network. I'm not the best with comps (but I'm always learning something new on them every day, have done for the last 10 years) and someone sent me an e-mail describing how to correctly do a "netsend".
For the un-technical in the audience, this is a way of sending a simple pop-up alert through DOS to make an alert pop-up on Windows with a small message of your choice and an "OK" button in the middle of it. It was like "Z******* has sent you a message. [Whatever the message] OK". Simple and sweet, but highly odd if you have never seen one before.
So I test it out with one of the guys on the team after I get his computer's Z number and we have a small laugh. After a few minutes though, I get bored and decide to up the ante a bit.
I get my manager's Z number while he's away from his desk and write it down on a notepad (they used to be on stickers on the base units). I walk back to me desk and wait a bit until my manager turns up. Up comes the DOS box and I send him the message.
"Pornography has been detected on your hard drive. A member of staff from I.T. will be with you shortly."
He went white. I could hear him swearing from my desk and could literally see the fear in his eyes. "What's this? Oh god, I'm fucked, I'm fucked..." He calls one of the other managers over who reads the message, notices the Z number tag on the message then walks around our desks as I sit there trying not to laugh. They find it on my comp and he comes over saying "You utter, utter bastard!!!" He spent the afternoon throwing rubber office stress toys at my head for the rest of the shift, but not until I set up another member of staff with the same prank for him lol.
Ah well, keeps us quiet.
( Jeccius Steam Borderlands 2 junkie, Sun 11 Jan 2009, 0:41, 5 replies)

Excellent e-prankery there.
Have a click while I look up how to do that.
(Juan Quar is clinging to her front teeth on, Sun 11 Jan 2009, 12:45, closed)

FYI, you don't need the machine name
at least, not in a domain - not too sure about workgroups. You could just have done

net send bosseslogin $filthtext

Although, you may note that under default installs of WinXP SP2 and above, the Messenger service (which governs the reception of these message) is disabled by default.

If you have admin creds, you can start it surrepticiously via

sc \\machine config messenger start= demand
sc \\machine start messenger

NB the space between start= and demand is important.

HTH
(_(_(_(_(_(_(_(_(_ =o.o=, Sun 11 Jan 2009, 18:04, closed)

Unless you forget
to specify a machine name and broadcast it to the entire domain of 5000+ machines

Ahem

*shuffles feet*
(Stringy, Sun 11 Jan 2009, 22:06, closed)

I didn't
but someone else did not long after that prank and the IT admins disabled it from our network after everyone in our 200+ staff office got "THIS IS FECKING AWESOME!!!!" turn up on their desktops.
( Jeccius Steam Borderlands 2 junkie, Sun 11 Jan 2009, 22:54, closed)

One of the guys at my previous office did this.
Unfortunately, the message was (and I quote verbatim) "Aren't the IT department shit?"

He had an unfortunate afternoon sweating about getting fired, since he had sent this to everyone: H.R., the CEO, and most powerful of all, the IT department.

Luckily, the IT dept. didn't take his job, they just took the piss for about the next 2 years.
( Amish Information Systems hates misplaced, commas, Mon 12 Jan 2009, 16:39, closed)