Before/after a trip to the nudist resort, my (ex) wife would often just wear a sarong loosely wrapped.
On the road the knot would invariably loosen up and become untied. I would then ask her if she was aware her tits were out; and she would claim she hadn't realized they were.
Besides truckers certainly seeing her tits, it also happened at a gas station when I pulled over for gas. When I looked over at her, one tit was hanging out; and I told her people walking by were seeing it. She gave me the old "oh?...I hadn't noticed...oh well..." LOL!
Same thing one day while we were on a dirt road leading to the resort. An older gentleman was getting mail from his mailbox. I looked at my wife and her sarong had completely dropped revealing both tits. Again..."hey...that guy can see your tits!" Her: "Oh...I hadn't noticed!" Well he sure did!