When the cat's away..........
Defined as when your wife goes away on holidays with her friend, sister, boyfriend....whatever and leaves you home alone. It can be treated just like a vacation but it's YOUR vacation from your spouse (highly recommended if you can accomodate her request).
Friend) Whatcha doing tonite Dave?
Dave) Nuthin' but enjoying my bachcation......me , my self and I can do whatever I want (until she gets home).