I like small conspiracies that have no explanation and are irrational. Here are a few that I've seen with a guy I know IRL:

The GDPR was meant to kill the internet. Or the European internet. I don't know how but this guy was very proactive and deleted his whole web site in retaliation. He had a web site to sell stuff, now he has no web site anymore. The fun stuff is that he was already GDPR compliant.

Vaccines against COVID were developed to kill old people. The proof I was given is "I have read on the internet that a 90 years old guy got a vaccine and he died!" Oh my god, that guy was 90 and he died? That's totally unexpected.

The hollow earth. It's a fun one since it exists since forever and got a revival thanks to the nazis. I can never understand why a rebellious "don't tread on me" idiot would blindly follow nazi theories.

Last but not least, Bluetooth is sending radiation to do "something," (don't know what) and is giving that guy bad headaches in the process. When he comes into our house, he's surrounded by Bluetooth but has no headaches, go figure.