One of my greatest pet peeves are characters with completely unrealistic heights. People can play what they want, but I will never be able to take a fifteen foot tall human, or a twenty foot tall Orc, seriously no matter how many wheaties they ate.
Alternatively, strangers who whisper me and give unsolicited “advice” about my characters based off of their own headcannons and opinions about how something should be written or portrayed. I know sometimes people want to help, but not everyone subscribes to the same headcannon. Often times people’s assumptions and “uhm ahkshuallys” are just flat out incorrect or, even worse, incredibly rude.