Alcohol
Diets...and le vin
Most diets forbid you to drink alcohol (whiskey and rye and grape and vodka, tequila and gin, all my friends). As a result, if you decide you need to drink that last quarter bottle of wine before you go on vacation, and you drink it, you will get seriously crunked up.
My lighter-drinking sister is going to be able to see me under the table in Europa.
:: chagrined ::