The expression derives from the common idiom or "Zip it," which means to stop talking or keep a secret. When used as a hypothetical (If I had a zipper...), it often conveys:
Indicating that someone is trying very hard not to reveal a confidential piece of information. Agar mere muh meinzip
Suggesting that the speaker's thoughts are being "locked away" by external pressure or social norms. The expression derives from the common idiom or
In some contexts, it can be a more somber metaphor for a lack of freedom of speech or the inability to protest against injustice. Contextual Interpretations command to be quiet. Zipper
To rein in your tongue (exercise self-control over what you say). "Zip it": A direct, sometimes rude, command to be quiet. Zipper, Zip up, Unzip and a few Useful English Sentences