First up: I was running no-script. The order page is under a different url (pay.ebay.com) so my whitelist of ebay.com didn't work.
I was trying to check if the PSPRINGTIME coupon would apply to an item, so I typed it into the coupon field and hit enter. This ordered the item with whatever card and address I used on my last order. I had to immediately request a cancel on the order from the seller. I never clicked an "order" button (or any button), and never was given any kind of order confirmation dialog.
