Reminds me of a time a few years ago when I was duck hunting a creek impoundment in the Nicolet National Forest in WI. There was a hiking trail that came fairly close to where we were hunting. Fall colors were at a peak, and two couples (tourists) were hiking the trail and taking photos, about 2 hours past sunrise. It was a sunny, calm, no-action day. The 2 women spotted our decoys in the water, and left the trail to get closer... for some good pictures of the "wildlife". They didn't see me and my buddy, hidden in the cat-tails, sitting on buckets, nor my nearby 12' jon boat under a camo net. Their husbands seemed to know they were decoys, stayed on the trail, but didn't let on.
When they were about 50 yds away, I gave a few soft "quacks" on my call. They kept "sneaking" closer (wearing red hoodies from U. of WI), taking pics. When they stopped about 20yds away from us - still oblivious to our presence - I gave a loud hail call that stopped mid-way when I burst into laughter. Scared the crap out of them... their husbands were literally on the ground laughing their asses off.
Their faces turned as red as their hoodies.