Doing multiple slacker-esque things concurrently.

A stupid person; it refers to the lack of surface area on an individual's brain. The general thought is that the more surface area (wrinkles, creases, etc.) a brain has, the smarter the person is. Conversely, a person with a smooth brain (no wrinkles) has less surface area and would therefore be stupid.

Similar to multi-tasking with computers, it involves engaging in a variety of applications on a computer. However, in multi-slacking, this definition is restricted to include one or more of the following: gaming, chatting, listening to music, web browsing (non-educational), hacking, pirating, posting on forums, watching videos, or viewing pr0n.

Doing two useless things at once.

Engaging in many small activities at once, none of which are productive. Usually, but not always, involving a computer and its applications (iTunes, AIM, YouTube, etc.), can also include watching a movie or TV show, listening to the radio, talking or texting on the phone, or any other ultimately trivial, meaningless activity.

Having two or more non-work related web pages, open on your work computer, at one time.

That combination of MySpace, chatting, and Wikipedia that Gen Y calls "work". The office internet take on "Work hard, play hard."