Slicehead
A Slice head is an emo / depressed / insane person whom is addicted to cutting themselves. Calling someone a slice head is like calling them stupid or crazy.
(Literal use) Did you see those cuts on Isaacs arms? He's obviously a slice head
(Insult use) Logan: Hey dude did you see the emoji movie? It was sick.
Shauna: You're a slicehead
(Insult use) Logan: Hey dude did you see the emoji movie? It was sick.
Shauna: You're a slicehead