Simply put, an away game of pocket ball!

When you eat dirt for the first time and leave your family to build a shack in the woods

When someone on MSN messenger (or other instant messenger systems like AIM) pretends they are away because they don't want to talk to you, but still want to talk to some people. Basically, it's the less rude form of blocking, but when you block someone they can't see you if you're on.