I'll have to call you back

There was a woman at Gristedes the other day who spent the entire time she was in the grocery store yammering on her cell phone. She stopped at one point to ask an employee where she could find the tuna, and the employee refused to answer the question until the woman got off the phone. She threw a fit. So what gives? When else is it totally inappropriate to be talking on your phone?
Sam, West Village

Cell phones are a great thing, but there is a time and a place. Most grocery store employees (or food service workers, or even the girl who folds shirts at the Gap) are hard workers and deserve respect. Taking five seconds out of a phone conversation that you could (and probably should) be having at another time is not showing them respect. If your phone rings in a store it's okay to pick it up, but, unless it's an emergency, tell your caller you'll get back to them later. This is especially true if you might need to exchange information. If you're going to ask a clerk a question, at least have the dignity to put the phone down. It's good to be paying attention at check out anyway; items get scanned twice, the cashier needs to know if your card is debit or credit. (And Gothamist once made it home with a jar of spaghetti sauce that we hadn't intended to buy. Which is not to say that cashiers are incompetent, just that it can't hurt to pay attention.)

It's also not polite to have phone conversations when you're: Out to dinner with someone; driving (with your hands-free earpiece, of course) while someone else is in the car; at work speaking loudly within earshot of six other people. Readers, feel free to add others.

Calling your husband to verify that he wanted steak for dinner and not chicken for the third night in a row is one thing; debating the relative merits of Sarah Michelle Gellar's portrayal of Daphne in the Scooby Doo sequel while standing at the check-out is something else entirely.