GoB refers to a group where the members are people who spend most of their time online. This is because they cannot socialize well out in the real world (or fail in the real world) and feel that the only place to make friends is through the internet. In general, people who are in a GoB group stick to themselves and try to mask their lack of life by acting big and important. It's frequently found that GoB members are weak in argument if they are by themselves.
"Wow that group is such a GoB"
Steve: "hey that group on that mmorpg you showed me was a real GoB."
John: "XD Yea i know"
8:18 <craig192> icceburn <-- what a cruddy name
8:19 <RIDLEY> yeah iceBITCH you suck
8:19 <icceburn> you guys need to quit being jerks
8:19 <RIDLEY> no we are GoB we rock
8:19 <kart_master> ^whs^
8:20 <craig192> icceburn nothing compairs to GoB. call us jerks again and i will ban you