How would I use LocalPlayer in a server script?

This is what I have in the classic paintball gun, from line 29 in 'Paintball'

    if humanoid ~= nil or localplayer then
        tagHumanoid(humanoid)
        humanoid:TakeDamage(damage)
        wait(1)
        untagHumanoid(humanoid)
    end

The entire script:

ball = script.Parent
damage = 50

function onTouched(hit)
    local humanoid = hit.Parent:FindFirstChild("Humanoid")
    if hit:getMass() < .5 * 200 then
        hit.BrickColor = ball.BrickColor
    end
for i=1, 1 do
    local s = Instance.new("Part")
    s.Shape = 1 
    s.formFactor = 2 
    s.Size = Vector3.new(1,.4,1)
    s.BrickColor = ball.BrickColor
    local v = Vector3.new(math.random9(-1,1), math.random(0,1), math.random(1,1))
    s.Velocity = 15 * v
    s.CFrame = CFrame.new(ball.Position + v, v)
    ball.BrickCleanup:clone().Parent = s
    s.BrickCleanup.Disabled = false
    s.Parent = game.Workspace   
end

if humanoid ~= nil then
     tagHumanoid(humanoid)
        humanoid:TakeDamage(damage)
        wait(1)
        untagHumanoid(humanoid)
end

connection:Disconnect()
ball.Parent = nil
end

function tagHumanoid(humanoid)
    local tag = ball:FindFirstChild("creator")
    if tag ~= nil then
        local new_tag = tag.clone()
    end
end

function untagHumanoid(humanoid)
    if humanoid ~= nil then
        local tag = humanoid:FindFirstChild("humanoid")
        if tag ~= nil then
            tag.Parent = nil
        end
    end
end

connection = ball.Touched:connect(onTouched)
wait(3)
ball.Parent = nil