look up any word, like cunt:
 
1.
1) A gesture to indicate that there is no harm done.
2) A gesture to indicate lack of effort.
1)-Hey man, thanks for carrying that piano for me!
-Ain't-a-thang
2)-Hey man, sorry for Denting your car
-Ain't-a-thang
3)-My bad!
-Ain't-a-thang
by Chingyiswack January 04, 2006