in the case of the rainbow gralat juggle, there's a 'joke' price that i had heard was a joke. I went to see what the real price was (5k i think) and then went 'no, I don't need to waste that much' and went to press where the 'cancel' button had been in the previous window. The buttons had been reversed, however, and I was not clever enough to notice.
In the case of the skull bounce, I was admiring the art on the halloween stock and definitely, without an ounce of uncertainty, pressed a button marked 'cancel' and had it buy anyway.