Here's another in the same vein, but this one has
to be tried verbally, you'll see what I mean in a moment.
Ask one of your family or friends:
"A farmer has 20 sick sheep, and one died, how many did he have left"?
Their answer is usually 25. When you tell them no, its 19, they'll look confused
while you explain you said sick not six.
Even though you said sick, people will usually hear six.
I must have tried this a hundred times over the years and have had only a handful of people reply correctly, 19, and more than a handful of arm punches for pulling their legs.