Usually “getting” a joke requires some subject knowledge. For example, you have to know who Michael Jackson is in order to understand Michael Jackson jokes. I came up with a joke which requires partial knowledge as well as partial ignorance. The joke is:
What emoji is missing on Chinese phones?
The character is “shǎo,” meaning “to lack.” To me it also looks like a smiley face. But to someone who knows the language, it doesn’t look like a smiley face—it looks like shǎo.
I think you can see the predicament. In order to get the joke, you have to know the character, but not well enough to sight-read it. This reminds me of stories about catching Soviet spies with the Stroop effect. Supposedly, suspects were presented with Russian words for colors, but typeset in different colors than what the words said. Then they were asked to go through the list and say what color each word was printed in. If you can’t read Russian, it’s very easy. But if you can read the word, your brain gets confused. In this way, you can test somebody for a lack of knowledge.