1. vulgar slang To be very stiff, rigid, or inflexible in one's posture or demeanor. Primarily heard in US. The guy trundled around the stage so gracelessly and awkwardly, as if he had a corncob up his butt. You'd think she has a corncob up her butt from the way she sits in class.

2. vulgar slang To be very rigid or inflexible in one's opinions or beliefs. Primarily heard in US. My grandfather had a real corncob up his butt when it came to people living together or having children before marriage.

3. vulgar slang To be irritable, unfriendly, or humorless. Primarily heard in US. Geez, it was just a joke—you must have a corncob up your butt or something. I wouldn't mess around with Mr. Daniels, he's got a corncob up his butt today.