[rracoonz]

You are on an afternoon hike with your fairly conservative wife (gf) and stop in a secluded opening for lunch. After eating, the two of you get naked and start having sex in the warmth of the sun. Suddenly, you catch a glint of sunlight flash off a pair binoculars and see two hikers have stopped and are spying on you.

Do you warn her and stop, or say nothing and continue having sex as they watch?

I wouldn't warn her at first and would definitely make sure she was on top and give them the thrill of seeing her body bouncing away. After she was beyond control and about to cum, I would let her know we were being watched.