have a corncob up ass
have a corncob up one's assand have a poker up one's ass
1. Inf. to be very stiff. (Use with caution.) How come you're acting so high-and-mighty with me? Do you have a corncob up your ass? He was a terrible actor, stiff and wooden. He looked like he had a poker up his ass.
2. Inf. to be very touchy or irritable. Wow! Old Mr. Webster really has a corncob up his ass this morning. Watch out! Tom has a poker up his ass and he's looking for you. Better make yourself scarce.