Brummel's Law
Brummel's Law states that once you've sworn off a particular habit or vice, an opportunity to engage in said habit or vice presents itself almost immediately.
Lara: Damn, I'm on the wagon for the next couple months, and now all of my friends suddenly want to have a social life. This sucks.
Roger: It's Brummel's Law!
Roger: It's Brummel's Law!