"Cork up" is a phrasal verb that means to hold back or restrain something from coming out or being exposed. Its antonyms can be "unleash", "release", "unseal", or "open up". These words refer to the action of letting something out or allowing it to flow freely. For example, when emotions are corked up, they can be unleashed if a person starts to cry or express their feelings. Likewise, a bottle of wine needs to be uncorked or unsealed to unleash the aroma and flavor inside. It's important to have a balance between corking up and unleashing, as withholding emotions or thoughts for too long can be harmful to one's mental health.