People taking your call in call centers are people, too--if you're having a problem with the product, odds are very good indeed that it isn't their fault. (Also note that they don't set the rules and usually can't change them.)
Always be aware of people in your immediate vicinity. If you accidentally bump into someone, excuse yourself! If you notice that your child is doing it, make them stop! (I once had a kid repeatedly whack me with her backpack while we were standing in line to ride Pirates of the Caribbean at Disneyland. Her father gave me a long-suffering look when he noticed it, but he didn't stop her.)
"Now everyone was giving her that kind of look UFOlogists get when they suddenly say, 'Hey, if you shade your eyes you can see it is just a flock of geese after all.'"
"You can't erase icing."
"I can't believe it doesn't work! I found it on the internet, man!"