On the way to a doctor's appointment for Ms. Dimples, the boys were having fun telling knock-knock jokes to each other. They still don't get it - but anyway....after a stretch of silence this came along:
5YO- "Mom, say 'knock-knock' to me"
Me - "Knock-knock"
5YO- "Who's there?"
Me - "The problem is I don't have a knock-knock joke"
5YO- "The problem is I don't have a knock-knock joke, who?"
Me - (hysterical laughing in the van)....
...then again, maybe they DO get it.