I've never been caught before, since I'm always pretty careful about where/when/how I do these things.
But...
There was one time I had left my browser on on my laptop and forgotten it, let a friend grab the laptop to go on gamefaqs... I had been browsing furaffinity (casually; not for porn) to see what stuff my watches have submitted, and left it on probably the most embarrassing thing I could have chosen. Let's just say cross-dressing Pokemon make for a lasting impression with friends. Thankfully there was technically nothing showing, but the mature roots were kind of implied in the pic...
It was more of a silly thing to laugh at than a really awkward experience. They all think I'm into that now, but I'm a good sport about it.
I choose not to correct them.
also: LOL wank-a-thon. that's pretty... uh... well...
How do you explain to a potential employer why your world record 222 orgasms is the first thing to pop up in a Google search? (I don't even want to know how that's physically possible...)