The phrase "gets the hang of" typically refers to a person mastering a particular skill or task. The antonyms for this phrase could include words like fail, struggle, stumble, misunderstand, or struggle to learn. These words convey the opposite meaning of "getting the hang of", indicating a lack of progress or difficulty in learning something new. It is important to note that while these antonyms may indicate initial struggles or setbacks, they do not imply a complete inability to learn, as everyone has their own pace and style of learning.