My sweet wife does end up exposing her panties every now and again - unintentionally though.
She isn't the most ladylike when exiting a car, and so if she's wearing a short dress or skirt, her panties are often exposed. I've seen her panties myself a couple of times, when I have been on her side of the car while she's getting out of the car - I suppose some of the valets/attendants at places we've been to have caught a glimpse of her panties
More generally, she isn't always great at crossing her legs and ensuring her panties are always hidden while dressed in a short dress/skirt. At a restaurant that we frequent, the seating areas are separated by a few short steps - hence from some of the lower areas, you almost get an eyeline view of the crotches of people at some tables on the higher area. On the wife's birthday, she was dressed to kill, in a short dress. When I was walking back to our table, I had a great view of my darling's lacy thong
She didn't realize she was being generous, and displaying some of her charms to some of the waitstaff