What the hell happened?
it occurred to me too while playing drums.
I stroke my head with a drumstick, and had the snare head filled with blood 
/me coming back on the drums these days 
Well the picture of the above instrumental construction doesn’t seem to require any use of the devices you hurt your head with.
Looks more like he busted his hands on a broken beercan or broken winebottle or something.
Or a bleeding nose.
Or he really put his blood into his performance! (ba da bum ts) 
Looks like he was playing in d-minor with a sharpened 6th… ouch.
