The antonyms for the word "playing up to" are "ignoring," "rebelling against," and "opposing." When someone is playing up to somebody, they are try to impress them by flattering or obeying them in some way. However, when someone ignores another person, they are not paying attention to them or giving them any special treatment. When someone rebels against another person, they are actively resisting their authority or control. Finally, when someone opposes another person, they are actively working against them or their goals. These antonyms show the opposite of trying to win someone over and instead demonstrate a lack of interest or active resistance towards them.