A liquid (saliva) that comes out of an instrument such as a saxophone trumpet and such due to blowing in it. A more politer/less disgusting way to say saliva came from an musical instrument.

(This term was first said by my music teacher)
"I tipped my saxophone upside down and out came the music juice."
"After a band rehearsal, there were music juice on the floor, everywhere!"
by Sherlock4869 December 3, 2016
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