No, this is not what I said to my students. This is what one student said to another student.
‘Shut up’ is a great phrase, isn’t it? The words are short and sharp and you can say them with real emotion.
‘To shut’ is a verb, and the past form and past participle (pp) are very easy to remember because they are ‘shut, shut’. Basically ‘to shut’ means the same as ‘to close’. For example ‘The shop closes/shuts at 7pm’, where either is used.
Be careful, don’t confuse the verb ‘to close’ with the adjective ‘close’, meaning ‘near’, the spellings are the same but the pronunciation is different, ‘to close’ sounds more like ‘to cloze’.
‘To close’ is better than ‘to shut’ for slow movements like flowers closing at night, and we also close roads (for repair), bank accounts and meetings. And ‘to shut’ is preferred for quick movements, like ‘shut the window, it’s freezing in here’.
So ‘shut up’ is a really strong phrase, but I’m sure my student had a very good reason to use it and, if you want to be even more forceful next time, you can try ‘shut your mouth!’