Photo: 68/Corbis

Really, you shouldn’t need a reason to be nice to your waiters. It’s a low-paying job that’s both physically and mentally demanding, and the least you can do is treat them kindly. But if you ever need a little extra motivation, a paper recently published in the journal Human Performance warns of what food-service workers do in retaliation to jerk customers.

Here’s what the 438 food service employees admitted to doing when a customer pissed them off, via the press release:

Making fun of the customers behind their backs (79 percent)

Lying (78 percent)

Purposefully making them wait longer for their order (65 percent)

Ignoring them (61 percent)

Being rude right back to the customer (52 percent)

Arguing (43 percent)

Flatly refusing a perfectly reasonable customer request (25 percent)

Confronting a customer about a crappy tip (19 percent)

Insulting the customer to his face (14 percent)

Secretly increasing the tip (as in, on a credit-card payment) (11 percent)

Doing something gross to the food (6 percent)

Threatening the customer (5 percent)

So most servers aren’t going to mess with your food, even if you make them mad — but, you know. They could. Stay on the safe side; it’s not that hard to be pleasant and tip well.