It is an exaggerated way of emphasising exclamation, typically used in sarcastic context, referring to a specific group of people who write in a similar manner during normal internet conversations, or think in a specific way (e.g. ricers).
For example, if I were to post a reply where I would say that I wished nitrous oxide to be implemented in LFS I could explain it in a rational fashion, with an attempt at correct and appropriate grammar etc., or I could go "z0mG!!11 I wan tT3h NAWZZzzZzz!111oneoneeleven".
For example, if I were to post a reply where I would say that I wished nitrous oxide to be implemented in LFS I could explain it in a rational fashion, with an attempt at correct and appropriate grammar etc., or I could go "z0mG!!11 I wan tT3h NAWZZzzZzz!111oneoneeleven".