Banks often process large payments ahead of small debit card charges made the same day -- a practice sometimes called reordering. It's a safeguard, banks say, to ensure important bills such as mortgage payments get paid off first -- but critics allege that reordering allows banks to increase the number of overdraft charges they collect.

It's a "gotcha-type practice," said Greg McBride, senior financial analyst at Bankrate.com

I call it "crap" and I don't know how many times I've been hit with compounding overdraft charges.

If you keep your receipts, you should be able to prove the order of purchases. But, of course, we all toss them away once we get them.

/Still, its a shiatty trick...

Buyer beware...
I still don't understand why people use debit cards.
Credit Cards offer the same conveniences with more consumer protections like being able to dispute charges etc. Just pay the thing off each month... or pay cash.