I've had none. I've always been too busy at work to surf the net. Plus is there really such a thing as 'accidental' mishaps?
'Ooh I clicked on 'blondes with big jugs do it rear end style' and I got 'blondes with big jugs do it rear end style'...how did that happen?
The only thing that I can think of is when I was researching pornographic literature* once (as I was thinking of writing some myself) the title of this story did not reflect the actual events that unfolded. I still read the whole thing but i've never looked at sex the same again.
*this was in the comfort of my own home. I do not read pornographic literature at work*