I think the more you worry about it, the more you might actually increase your chances of saying something regretful. So, just try to forget about it.
Also, a few people hit the nail on the head with the following:
(1) Anesthesia is certainly fun while you're under, especially if you don't use drugs often or at all, so enjoy the ride.
(2) Your mouth will be packed with gauze, so it's unlikely you'll blurt out anything intelligible anyway.
(3) You'll likely be with a dental assistant or a nurse right afterward, and not with a family member until you've recovered a bit (unless you ask).
(4) The aftermath is considerably worse than anything you might accidentally say. Worry more about what and how you plan to eat comfortably.
From personal experience, make sure you follow your dentist's orders and don't try to rush your recovery; it'll only make things hurt worse. Here's to a speedy recovery!