Advice on where to start

[fauxpas09]

Hi guys, a friend of mine thinks it would be funny if I could write something which would periodically display a custom message on the target computer, like a pop up window literally. It's only really for this one computer.

Anyway I'm just interested in how I would even start something like this, the best language to use ect.

I'm fairly competent with Java.

Thanks in advance.

Just a side note, the whole purpose is to display some funny messages that will confuse our friend ect, I'm not looking to do anything harmful or malicious.

[pretentious]

I'm thinking this would be pretty easy to do with virtually any language.
in Java i guess you would initialise a new Frame when ever time == something. though you would need to have the main program running the whole time

[WallShadow]

Actually on the topic of this, does anyone know a way to run a java class file or java Thread in a way that no windows / consoles / prompts come up? I've been kind of trying to do the same thing as OP for a while now.