But, often, there are jokes I don't understand, then someone "explains" it, or gives a hint, and then realisation dawns and I can appreciate and enjoy the joke - if people cannot question or explain them, then no one learns anything
If a joke fails to be a joke because of obvious errors, is it not right to point it out ?
Otherwise, just type any random sequence of words and claim it is funny .
e,g,
Wife : Hello dear nice day at work ?
Husband : Oh gods, the dentist ate the lizard.