Deadpan

Deadpan is a form of comic delivery in which humor is presented without a change in emotion or body language, usually speaking in a casual, monotone or cantankerous voice and expressing an unflappably calm, archly insincere or artificially grave demeanor. This delivery is also called dry humor or dry wit; when the intent, but not the presentation, is humorous, blunt, oblique, sarcastic or apparently unintentional.