function doubleD(ply, hitgroup, dmginfo)
    if (hitgroup == HITGROUP_HEAD) then
        for k, v in pairs(player.GetAll()) do
            v:EmitSound("hattrick.wav")
            dmginfo:ScaleDamage(2)
        end
    end
end
hook.Add("ScalePlayerDamage", "DamageDouble", doubleD)

function DamageScaleHattrick(ply, hitgroup, dmginfo)
    if (hitgroup == HITGROUP_HEAD) then
    end
end
hook.Add("PlayerDeath", "myblackass", DamageScaleHattrick)