I know what "listen up" means but I am not sure what "up" means and why it has to be "up"?
I asked it to ChatGPT.
Following is what it tells me about it.
Breaking Down the Phrase:
Listen: This simply means to pay attention to sound, especially with the intention of hearing something specific.
Up: In this context, "up" is used as an intensifier. It doesn't have a literal spatial meaning here. Instead, it serves to make the command stronger and more urgent.
But It think it has some specific meaning.
Can anyone tell me about it more clearly?