Lyric discussion by AreWeDancer 

Cover art for Balaclava lyrics by Arctic Monkeys

He is comparing his balaclava (a mask) as the mask he uses to hide his emotions and true self from any girl he happens to be hooking up with. He is comparing relationships and falling in love to committing some sort of crime (usually someone ends up hurt in the end).

He says will it end in salty cheeks and runny makeup (will the girl get hurt?).. or a boy bewildered and scorned (will the boy get hurt)? And when he says "or will blood run down the face of a boy?".. (intending when he gets hurt, he hurts deeply, as if to say "you may cry mere tears, but I cry blood."). So he keeps on the balaclava (doesn't offer his true emotions or love to a girl, in order to prevent being vulnerable).

"Now the shaggers perform, And the daggers are drawn, Who's the crooks in this crime?" Shagging (making love, or getting involved) can be as brutal and painful as a knife-fight.

In the end, she's pleading with him to take off the balaclava (to get close, show me your feelings) and he says, "I'd much rather keep on the mask" (not get emotionally attached).

thank you - thought i had to explain it to everyone for a second there lol!