The word's origin is thought to be a typo of the already incorrect labtop.
The mistake was unexpectedly embraced -- airhead teenage girls and one wannabe L337 asian teen rejoiced in the purchase of their new "labtob" notebook computers.
Utterance of the word typically precedes a swift blow to the face with said computer.
Eric: I just got a new labtob. It can hack into the Pentagon and beat you at Starcraft at the same time.
Me: Laptop.
Eric: No it's labtob.
Me: Lap. Top. It sits on the top of your lap.
Eric: Mine is faster than yours.
What wannabe thugs and other ghetto people call laptops. Also used by ignorantwhite people. When one says labtop, the "a" is usually excessively stressed.
I just got me a new laaaabtop.
--------------------------------------------------------------------
Ghetto person: "Can you fix my laaaabtop?"
Me: "Sorry, I don't work on labtops."
Ghetto person: "What you mean you don't work on laaaabtops?"
Me: "I don't work on ficticious items. Now if you have a LAPtop, I can fix that."
Ghetto person: "That's what I said, laaaabtop."
Me: "*looks down with hand over eyes and shakes head* Gimme the fuckingcomputer."