Is 251 years old a secret code?

Okay. I'm perplexed and this has been gnawing at me for a couple of days now. Can anyone help with my quest for an answer to this question?

Is listing your age on an information page as 251 a secret code for a select group?

I encountered this when I view my profile and click on a specific interest to see who else shares the commonality. For example, when I select my book 'Animals in Translation', 57 other bloggers who have listed the book pop up. When viewing the members, I noted that 7 of the 57 list their age as one that is obviously wrong. All are women and one says she is 501, and the rest say they are 251. All 6 of the 57 are 251!? I have also encountered this same age at numerous other profile listings. 

Is this a code for 'lesbian'? Or indicating the user has a great sense of humor? Or has the original lister started a trend? 

Don't you find this intriguing? I has to be a secret code of some kind. I'm convinced! Maybe not lesbian, but it's got to be something... Anyone have any ideas?

Or, maybe I've got it all wrong and this is in dog years. 35.8. Nah. That doesn't make sense.