Wow. Now that you mention it, when I was close to a narcissistic sociopath, she told me that I laugh at my own jokes, and that was how she knew they were jokes. She claimed to have a "highly sophisticated sense of humor" and belittled my sense of humor.
After her... feedback... I made sure I didn't laugh at my own jokes. She took my jokes seriously and in response to them either lashed out at me or gave me condescending lectures. She genuinely seemed to not understand that I was joking.
I came to believe she didn't have a sense of humor.