This unintentionally hilarious parent’s primer to computer slang from Microsoft’s “Child Safety” department is filled with choice tips such as:

Letters can be substituted for other letters that may sound alike. Using “Z” for a final letter S, and “X” for words ending in the letters C or K is common. For example, leetspeekers might refer to their computer “5x1llz” (skills).

Rules of grammar are rarely obeyed. Many leetspeekers will capitalize every letter except for vowels (LiKe THiS) and otherwise reject conventional English style and grammar.

Make sure to let them know the information was useful to you!

Edited to add: El Reg has their own take on the matter.