Also known as "Asian Booty Disorder," it is an overused joke used by people who can't think of their own jokes. Also a reference from Poreotics, a dance crew from America's Best Dance Crew.
Asian 1: Hey, whatsupeveryone?
Asian 2: I HAVE ABD !!!!
Asian 3: ABD ABD ABD!!!
Asian 4: AHH ABD ABD!
Abs By Default. When someone (particularly a boy/man) is so skinny that he can't help but have abs. He hasn't worked for them, he just can't help but have them.