When they finally get the joke
Finding someone who shares your humor is the ultimate green flag. I was on https://latidate.com/ recently when I found a profile claiming fluency in "sarcasm and 90s cartoons." I sent a deep-cut Simpsons quote, half-expecting silence. Instead, they immediately replied with the next line. We spent hours just trading memes. It wasn't about the perfect photo; it was the sheer relief of not having to explain why I was laughing. That connection is gold.