Slang term for defecation. Sometimes rumored to have been invented by George Washington while crossing the Potomac. It is a general term for the action of defecation, but can be altered after the "cracking" to describe the volume or intensity of the defecation.
"Bretheren...observe as I go forth and crack ten unto this mighty river."
"Hey guys, I totally cracked fifteen in that dumpster!"
"I gotta crack ten, be right back."