Even if her life depended on it, my wife cannot tell a joke. In all other ways, she’s brilliant. (Beautiful too.) In fact, the way she ruins a joke is in and of itself amusing and (if I may say so) adorable.
She starts off with the premise of the joke (what professional comics call the setup), then she starts to crack up. You can see by the quirky look on her face that she’s thinking of the punch line (what comics call the payoff). Anticipation clouds her story line. Then she starts laughing, giggling, and breaking up . . . until she can continue telling the joke no longer.