Wtflol is a combination of wtf - what the f**k and lol - laughing out loud. It's meaning is simple and expresses a state of amusement and being surprised at the same tim. Used in mmo games when a lowbie char is trying to pwn u, gets flagged and then being 1shot by you.
PwnZ0r: omg, this dude came and tried to anchor me. So I hit him and dealed 4567 dmg.
Try2ownMe: wtflol :)