This reminds me of the time when I spoke very little English, didn't know much about the American culture or the West in general, and struggled every single day to communicate as an adult through 5th grade level English vocabulary (while trying to retain some dignity). It doesn't matter whether it's done out of good intention; it's exactly this type of humor that embarrassed me, shamed me in public, took away any confidence I might have had to the point where I was so fearful I didn't want to converse with anyone in English. It told me that the person wanted to say/do what they wanted to say/do so much they couldn't care less whether I'd understand or what my failure to understand would make me feel.
Those who speak English as an additional language, especially when they're still in the initial stage of learning, already struggle on a daily basis. The knock-knock jokes, guy-walks-into-a-bar jokes, etc., don't make it any easier for them.
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