Well, the general rules seem to be that you should never go out for your food. Send someone to get it for you or have it delivered. To add fuel to the superstitious fire, I've had two cardiac arrests in the last two months that came within 10 minutes of my departure to pick up food.
People also seem very sensitive to the words "slow" and "quiet".
And if you're doing something important like changing an onboard O2 tank, or something fun like playing wiffle ball in the parking lot, never mention the lack of calls. This includes commentary in both a positive and negative light. "Thank goodness it's been slow so we can ____." is a killer.