l337 speak. I guess you could call it this generations valley girl or dude speak. I don't particularly care to use it much myself, but it cracks me up to see and here it used in conversational English. Especially when people are using it seriously instead of ironically. I guess every group likes to have their own special code or language that differentiates them from those around them. This shirt can be translated by any FPS or MMO players you may know. The shirt can be found here. If you want to take a crack at translating more l337 try this.
H3||0 h0w 4r3 y0u d01n6 70d4y? 1 4m v3ry w3|| 7h4nk y0u. 4nd by 7h3 w4y 1 |0v3 y0ur 7-5h1r7 17 r0ck5!
If you have trouble you can paste it into this translator.