I've told the story before and it's more of, we were caught taking the photo, than anyone actually seeing anything. On a lonely stretch of interstate, I had her flash me while next to the "Welcome to..." state sign. Of course, she doesn't want anyone seeing and she's got a good view of what's coming her direction. I noticed a car coming the other way and really didn't think anything of it as we'd be done before it got close enough. But I miscalculated and it was going faster than I thought, because by the time she put her shirt down, it was close enough to see what we were doing and as it passed, it honked at us, scaring the hell out of her.
She's still of the opinion that they actually saw her boobs, but I know her shirt was down well before they passed. Most they would have seen was her bare lower back. Still damn funny to think about.