Do you trust that your birthday is your birthday?

I watch this great YouTuber, his show is called Law Talk With Mike, and he shows clips of people being stupid in court. His favourite cases are so-called Sovereign Citizens (these are really weird people who read some legal things on the Internet and insist that they don't have to follow the same laws the rest of us do, so they don't have driver's licenses or car insurance, etc.)

Anyway there was a great case the other day when the judge was verifying that the defendant was 51 years old. He said "I have been told that I am, assuming that's when I was born, but I wasn't conscious to actually know if that's when I was born." It was typical stupid SovCit word play, but it was kind of funny because I did realize that we do TRUST people that our birthday is our birthday. I did think for a minute though: What if people got together and said "Ok, we're going to tell little johngreenink that his birthday is May 27, ok?" And they all agreed. It's totally stupid but I laughed a little.