My husband dared me once to have sex outside in a semi-public area. On the sand dunes on a nude beach in England. There is something really special about making out in the open air. What made this extra special was that by the time we were well into things and too far along to stop we realised that we were being watched by another couple who were nude as well. We just kept going and after we had finished the other couple smiled at us and moved away.