I disagree with the very concept of “shut up”. It denotes a rude manner of implying that someone may not speak due to you telling them not to, hence “shut up”. It denotes that with a single phrase you can withdraw from every thing. It is a cheap way to avoid confrontation. This is highly illogical and counterintuitive in the grand scheme of things. So just because you want someone to be quiet doesn’t mean you have the authority to control their ability to speak.