Like maybe a week or so before a wedding, conference, reunion, beach vacation, or other function in real America that requires me to squeeze my baker's dozen of Pillsbury crescent dinner rolls into a dress from five weddings ago. In other words, the sort of event where knee-high Xtra-Tuff rain boots and a three-layer ski jacket aren't necessarily appropriate to the weather or the occasion.
I've dubbed pursuit of the requisite germs "The Dirty Mayo/Kiddie Spoon-Lick Cleanse." It's pretty easy, at least on your wallet if not your body. You just go to the nearest gas station convenience store and buy and eat a pre-wrapped egg salad sandwich. Substitute sushi if egg salad is unavailable. Wait 24 hours and watch your entire gastrointestinal tract turn inside out. Voila! You fit into the dress!
Alternatively, find a friend whose child has been home from day care for the preceding two days due to nonstop shitting and puking. Go to their house and lick every spoon in the kitchen sink. Follow final two steps above.
This is SO much easier than exerting actual willpower in diet or exercise. It's also much faster and cheaper than the "Thai Prison Diet," which requires being arrested for smuggling hash out of Bangkok ala Claire Danes in "Brokedown Palace" and spending the better part of a year scrapping for rations of rice and fish sauce on the floor of an 8 x 8 concrete cell while several belligerent old Thai ladies dressed in paramilitary garb yell incomprehensible directives at you and beat you with sticks for non-compliance.
According to Claire, you come out of there with a bangin' bod and only the mildest touch of PTSD. But don't worry: If you lack the resources and intrepid spirit necessary to commit to the "Thai Prison Diet" in time for your special day, the "Dirty-Mayo/Kiddie Spoon-Lick Cleanse" is TOTALLY your second best option.