straight face n. A face that betrays no sign of emotion.
joke n. Something said or done to evoke laughter or amusement, especially an amusing story with a punch line.

straight faced joke example Bernadette returned home earlier tonight from Sam's Club (her first trip) with a ridiculous family size 6-pack of Mentadent toothpaste refills. Several hours later I walk into the living room while she's watching a movie, holding an old empty Mentadent refill.
Me: Hey Bern, this is out of toothpaste. Do we...have anymore...or...?

asshole n. A thoroughly contemptible, detestable person who makes stupid straight faced jokes.