Blogger LAPD Wife recounts that when she checked out recently at Costco, the clerk ringing her up said she could buy either the Sudafed in her cart or the Nyquil—but not both. Both are on the shelves, and no explanation was offered. She figured it was some corporate policy based on fears that those cold remedies are used in methamphetamine labs, a belief her LAPD husband had doubts about. Anyway, she went home with medicine for her children but not her sniffling spouse. (via ChangeLA.com)

* Probable answer: State law (specifically California Health and Safety Code section 11100) bars the sale of more than three packages (or nine grams) of certain over-the-counter drugs at a time. Since it's Costco, it's likely she was buying multiple bottles. Thanks to Vic P for the code section.