I just saw this on a place I won't bother linking:
This october has 5 fridays, 5 saturdays and 5 sundays. This happens only every 823 years. And I am grounded all month!
Really, it's not worth linking to because it's everywhere
There are variations, of course, 5 sunday/monday/tuesdays, different months, etc.
But why are people falling for that? I mean, it's pretty obvious if you think 2 minutes that there's no way it can be true!
The length of october is fixed (31 days).
Since weeks are 7 days, you have 4 weeks + 3 days in october.
If october starts on a friday, those last three days are going to be friday/saturday/sunday.
So, for this thing to be true, October 1st would have to be a friday only once every 823 years. Sounds pretty stupid when you say it that way, right?
I really have no idea how anyone with half a brain can fall for it, but I have seen people I know have a functional cortex do it. Comments encouraged :-)