No-shows for the last appointment slot of the day.
If your dog is acting like a wild animal-flailing, screaming and biting while on the table under no circumstances should you hug, coddle, baby talk or feed her treats. She is not a "good girl" and it is not "ok." Performing these actions only reinforce that this behavior is desired and acceptable, the opposite of which is true.
Calling at 4:20 because your dog is "dying." I'm quite certain it was apparent your dog was "dying" prior to 4:20.
Obtaining a large breed dog and failing to pursue any kind of obedience or socialization training.
Leaving poorly behaved children unattended in the lobby.
Bringing poorly behaved children into the exam room.
Arriving late to your appointment, not apologizing and suddenly having a lot of questions about health issues your new puppy may develop since you did not do any breed research ahead of time.
Allowing a problem to go on for a month, making an appointment towards the end of the day, showing up late, and being unable to make any decisions without calling your wife.
Don't worry, tomorrow there is a happy story.