The Walking Dead has been around for a while now, which means the show's many characters have had the opportunity to make some absolutely idiotic decisions over the years. When you think about it, there is no way this group of survivors could actually survive given the choices they have made. However, they continue to eek out an existence in spite of numerous villains, the threat of zombies literally taking a bite out of them, and their penchant for making some of the worst decisions in the history of horror fiction.
To be fair, it's easy to sit on the couch and judge the actions of a group of people trying to survive the apocalypse, but many of the decisions the key characters have made on the series don't make a lot of sense. Arguably, some were made in the heat of the moment and were simply bad choices, but others qualify as the biggest bonehead moves in all of television.
Throughout her time on the series, Lori was something of a frustrating character. A lot of fans didn't like that she hooked up with Shane, and while that may have been a crappy decision, it wasn't necessarily a bad one. For all she knew, her husband was dead, and Shane was there for her and Carl. Looking beyond that decision, she didn't make a lot of great ones up until her death. The most idiotic of them had to be the time she left Carl to look for Rick without bothering to tell anyone.
She made this choice when Rick didn't come back from the city. Lori was freaking out, which is understandable, but instead of organizing a party to find her husband, she just up and left. She didn't tell anyone or organize any kind of real effort. All she did was leave - and her kid cried at the prospect of losing both his parents. She ended up crashing her car into a walker and nearly killing herself, but Shane was able to find and rescue her. It was a stupid decision that luckily didn't have too many negative consequences - if you exclude the anguish she caused her son.
To be fair, Sophia was just a child when she was separated from the group. However, instead of running towards the living, she went off and partied with the dead. Sophia should have known better than to run away from the group. And she didn't just run a few hundred feet - she fled the area by several miles. After she went missing, the group had to split up to find her, and it fractured the already fragile band of survivors.
Eventually, she re-emerged as one of the walkers stuck in Herschel's barn. The revelation helped close out her story, and also proved that the best way to survive is to remain with the group. Her decision to run away may have been more related to her age than anything else, but that doesn't make it any less of a terrible decision.
Beth was held hostage for a little bit in a hospital run by a woman known as Officer Dawn. The whole setting was somewhat terrifying and disturbing; however, Beth was ultimately rescued. The group tracked her down to the hospital and met up with her in a hallway where they arranged to take Beth off Dawn's hands. It was all going perfectly fine until the moment Beth decided to stab Dawn. The officer responded by shooting Beth in the head; consequently, Daryl shot and killed Dawn.
It all went down in a split-second and left the group - as well as the audience - wondering what just happened. It was an instantaneous moment of violence, and there was absolutely no reason for it. Beth was free and clear but felt she had to exact some form of revenge at the last moment. Her decision resulted in her death, and this scene stands as one of the strangest and most hated of the series.
In a world overrun by the dead, it's important to keep your resources close at hand. That includes everything from a bottle of pills to a can of food, but it also means the people with the knowledge and skills needed to keep folks alive. An engineer is good at building bridges and maintaining buildings, but a doctor is vital for the survival of everyone. They are rare in the world of TWD, which is why it makes absolutely no sense that Negan would kill the only one he had.
Upon learning Sherry was dead and had plotted with the good doctor behind his back, Negan doled out his own form of justice. Granted, it was all a ruse pulled off by Dwight, but that hardly mattered to Negan, who wouldn't even let the doc defend himself. He threatened to burn the doctor's face with an iron but instead picked the man up and threw him face-first into an incinerator. Doctors are hardly expendable, but Negan didn't even think about that when he made this stupid decision.