A person, group, or object made up of several different elements that normally would not be put together.
"His ship had a very grabastic construction, due to the many spare parts he used to build it."
"You are the lowest form of life on Earth. You are not even human, fucking beings. You are nothing but unorganized grabastic pieces of amphibian shit."
I was on a conference call with work, the Sr. V.P. came on and it went from a simple 20 minute call to ballsuck central, it turned into an episode of Battlestar Grabastica.
adj. inclined to play grabass (bumble around and waste time in a group of 2 or more). grabass is an imaginary game of unsurpassed stupidity in which the object is to grab someone's ass or have your ass grabbed, or something.