This is too funny.. especially since I've dealt with the public in every job since I was 16.. including the BMV.. and I gotta tell you it's not the workers there that are horrible people, it's the PUBLIC that makes them that way. You think you've been yelled at, at a job.. not till you've worked the BMV/DMV..
I agree with the poster that said.. don't do the sly/tell people off in a nice way. Believe me I've done it all.. and occasionally that one still rears it's ugly head

But the kill'em with kindness works best.. Smile, be nice, AGREE with everything they say.. UNLESS they swear at you or call YOU names.. that's a deal breaker..no pay is worth that.
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Rhonda, Bailey, Josie and my angel Bella Rue'
"Until one has loved an animal, a part of one's soul remains unawakened."
~Anatole France~