Assbooker is a Facebook term that can be used in any social network. The term comes from being a "smart-ass", hence the Ass, and Facebook, hence the "booker". Basically, an Assbooker is a person who makes smart-ass remark on a Facebook friends staus, picture, etc.
1. Assbook (otherwise known as the "booty call social network")is “An online directory that connects people through whom they have hooked up with.” The facebook’s “poke” feature — has been reinvented as “tap that ass” feature. Instead of messages, users receive “booty calls.”
2. Obviously much cooler than Facebook.