A corruption of lol into lawl, and what into wut. Then they get sticked together.
Reid: I just ate a baby!
Lawlwut is when you are 'lol'ing at something really stupid or something you have no idea what it is, Yet it is funny.
Dog: Is the kettle still hot? I want some coffee.
Me: Umm, Youre talking?
Dog:Hai Hai Hai...