I suppose I better start the ball rolling.
This is a little personal one, happened years ago but I still find it odd when I think about it.
This was about 15 years ago, both my mum and dad were ill with bad colds and couldn't get out. While I was visiting my dad asked if I would pop to the cash machine and get some cash out for them.
We both banked with the same bank so I knew where there was a machine. My dad always liked to use the same one, I think he believed they still charged you if you used another bank's machine.
Anyway I asked for his PIN and was astounded to find his number was exactly the same as mine except for the last digit being the next up from mine, for example his being 4321 and mine being 4322.
I asked him how long he'd had the number and like me he'd had it since his first debit card, changed it the first time and kept the same number since. Neither of us had any reason to ask or know each others numbers in the past and they had no significance to either of us, they were both just a totally random number choice.
Maybe it's just me but I find that quite weird