You have to take a crap so bad and because it's fully brewed it's pressing upon your sphincter. The skin on your entire body breaks out into goosebumps.
"We have to pull over, man. It's been 4 hours since we left and I have to take a dump so bad that I have shitbumps! See them?"
Nickname given to bales of marijuana thrown overboard or out of airplanes. Origin is reportedly from members of the US Coast Guard in the area of Southern Florida.