I find it very upsetting that nobody knows what pwl means, or just didn't bother to submit a legit definition of a pwl until now.
A pwl is an owl that pwns.
PWLOL, now taking the spot of lol's all over the world. PWLOL is a more dramatic take on the original lol, and means, Peeing while laughing, Confuse your friends with this new shortcut.