I remember hearing a comedian talk about how people mess up saying their phone number out loud.  As Americans with 10-digit phone numbers, we expect a spoken format like this: 
1,2,3 ... 4,5,6 ... 7,8,9,0
The comedian said he was talking to someone who offered to give him their phone number.  It went like this: 
1,2,3,4 ... 5 ... 6,7,8,9,0
I just had a similar experience with my credit card number.  I called a place to pay a bill over the phone, and I gave them my credit card number like this: 
1,2,3,4 ... 5,6,7,8 ... 1,2,3,4 ... 5,6,7,8
Credit card numbers are conveniently divided into 4 groups of 4 digits for that exact reason (or so I would presume) (except American Express, but they're stupid).  After I gave the woman my number, she read it back to me to verify.  It went like this: 
1,2,3 ... 4,5,6 ... 7,8,1,2,3,4,5,6,7,8
My head almost exploded.  How could someone come to the conclusion that reading a group of 16 digits in that way would be even close to logical?  I realize not everybody thinks like me, but give me a break.  This is ridiculous.  Sometimes I think things happen just to mess with me. 

Another similar thing happened twice today as I payed other bills over the phone (their stupid websites were broken).  I received a confirmation number from that automated electronic lady that navigates you through all those stupid phone menus.  The first one wasn't too bad; it was 6 digits, which is short enough to not divide into separate parts: 
3,4,9,8,2,5
But even though it was short, I could barely follow it because it came out of her mouth (or whatever she talks out of) like an explosion.  Of course it took about 2 minutes for her to get through stating my 16-digit credit card number, but it took about 0.5 seconds to give me the 6-digit verification number.  It was less of a "3,4,9,8,2,5" and more like a "349825".  A few minutes later, I payed a different bill over the phone and was given a 9-digit verification number.  It was no less than twice as ridiculous.  I started writing it down and could barely keep up.  Plus, I had no idea when it would end.  What an experience. 

Update (2007-08-20 10:46am):  I just realized this is very similar to this. #language