Well, I'm not lucky enough for it to have happened to me. Just going to claim it doesn't happen as much to blokes and move on (seriously @IncognitoSCN, 2!) Happened to a friend of mine just walking up a hill. She had an asthma attack, leant against a lamp post to catch her breath, and someone...
I often like to be clothed while she's nude - usually for a power dynamic. But I do enjoy exercising naked while she watches. Which often turns into that.