The visitors? My parents.
The special prep? Buying toilet paper. Lots and lots of toilet paper.
Lest I mislead those of you with senses of humor similar to my own, my parents are not (ahem) "crappy" people. That is to say, they don't make copious use of this most essential personal cleanliness tool. But their visits always evoke that Pavlovian response in me: Omigosh! Mom's coming! I need to go buy toilet paper! Even if the basement is already well-stocked with ample supply, I cannot fight the urge to go buy just one more package.
So, you ask, since they're not over-zealous with the TP use, why the panic response?
In a nutshell: Parents visited my first little apartment paid for with my first teaching job. Snowed in - raging blizzard, several feet of snow. Very little groceries. Down to one roll of toilet paper even before they got there. (Bree Hodge, I definitely was not.) Waited out the worst of the storm. Dug out my parents' Ford Escort to brave the elements and remedy a potentially disastrous situation. Swung by my then-boyfriend/now-husband's place to pick him up (me so hoping he'd get snowed in with us.) Ate at a nearly deserted Bob Evans with travelers stranded by the storm. Grabbed the very last package of toilet paper at the grocery store. Dropped off then-boyfriend/now-husband back at his place. (Darn!) Slipped and slid our way back to my place. Endured endless ribbing about "what might have been," had we remained TP-less.
And so, to this day, I am never, never, never short on toilet paper when my parents come to visit.