My wife and I have always had a fantasy of dogging. That's more of a UK term which means driving out to a car park (parking lot/area) and rolling down the window so strangers can feel up your wife.
We've never actually done it but want to one day and we do take pictures and visit car parks to practice which is great fun if you've got the spirit.
You never know when a bloke will appear to fondle your wife's tits.