not related to playing an actual instrument, the crimson violin refers to cutting your own wrists. the violin is the sawing motion one makes (across the street not down it!) and the crimson is the blood shed. makes it alot easier and more casual to ask if said person is a cutter
"Laura is wearing long sleeve shirts lately and its july."
"does she play the crimson violin?"
"haha maybe! i wouldnt be surprised."
"wow that was very casual and easier than asking if she rips her wrists apart."
"your right. i love UD