1) Do not lose the vibrating toy in your sub's butt. 2) Make sure the toy is meant for the right hole. This is very important. Just saying. It's very awkward having to plop it out like you layed a golden egg.
The above is just a fabricated story and never happened to me. I've also been known to spin a few tall tales. Sex has never sent me to the er, but if it did I know I could count on my BDSM partner to kick me out of the car on the curb and call the er to come out and get me.
Above all, don't forget the fucking peanut butter!!!! Very important.
All jokes aside, spend some time in another realm.