Brought to you by unintentional contemplation of Backstory Revision syndrome and a hapless university student who ended up joining the military in a different universe:
Always keep good beer in your fridge, because you never know what sort of supernatural creature may show up to raid it.
To be fair, the “supernatural creature” in question didn’t show up for the express purpose of raiding the refrigerator; it was merely convenient to do so before leaving again. I don’t know if he liked the beer he stole, either; it never even occurred to me to ask. I’m just the uncredited-by-choice co-author, after all, so it’s probably none of my business. (Maybe I should ask, now that I think of it. Perhaps there is additional backstory detail in there somewhere… *shakes head*)