look up any word, like cunt:
 
1.
to drop a cob is to engage in the act of defecation, usually but not always atop a toilet.

probably so said because of the turds resemblance in size and shape to a corn cob.
I'll be right back I gotta go drop a serious cob

I feel 10 lbs lighter after dropping that cob, I'm totally refreshed! Thank god for fiber supplements.
by vincent black shadow March 06, 2005
11 2