What compels a man to have his wife expose herself to truck drives and what compels a woman to do so?

What compels a man to have his wife expose herself to truck drives and what compels a woman to do so?
For both it adds a level of excitement that could be missing in their love life. For the man, it's a way of showing off what's his to those who can't have it. For a woman... well, it's a way of showing off what's her's to those who can't have it...