sh_advert_revert.lua

--Put me in darkrp_modules/advert_revert/sh_advert_revert.lua for it to work!!!!
timer.Simple( 30, function()
    DarkRP.addPhrase('en', 'advert', '[Advert]')
    local billboardfunction = DarkRP.getChatCommand("advert")
    billboardfunction = billboardfunction['callback']
    DarkRP.removeChatCommand("advert")
        --From darkrp before the update to remove this. Check the commits
     local function PlayerAdvertise(ply, args)
        if args == "" then
            DarkRP.notify(ply, 1, 4, DarkRP.getPhrase("invalid_x", "argument", ""))
            return ""
        end
        local DoSay = function(text)
            if text == "" then
                DarkRP.notify(ply, 1, 4, DarkRP.getPhrase("invalid_x", "argument", ""))
                return
            end
            for k,v in pairs(player.GetAll()) do
                local col = team.GetColor(ply:Team())
                DarkRP.talkToPerson(v, col, DarkRP.getPhrase("advert") .. " " .. ply:Nick(), Color(255, 255, 0, 255), text, ply)
            end
        end
        return args, DoSay
    end
    DarkRP.declareChatCommand{
        command = "billboard",
        description = "Create a billboard holding an advertisement.",
        delay = 1.5
    }
    DarkRP.declareChatCommand{
        command = "advert",
        description = "Advertise something to everyone in the server.",
        delay = 1.5
     }


    if SERVER then
        DarkRP.defineChatCommand("advert", PlayerAdvertise, 1.5)
        DarkRP.defineChatCommand("billboard", billboardfunction)
    end
end)
--[[
LICENSE
You are free to modify and distribute this, but you must keep all names of anyone whom has done an edit.
Orignal Author: Andreblue
]]

why 30 for timer.simple. And [Advert] before players name isn't yellow.

Why even use a timer? I'm sure 30 seconds is more then enough time but this could still cause issues with updates, load order etc...

You can easily use the loadCustomDarkRPItems hook instead.
Maybe even throw in a 1 second timer to make sure that this gets ran last (to avoid conflicts for future proofing).

Somehow it doesnt work on my Server.

I put the file into server/garrysmod/addons/darkrpmodification/lua/darkrp_modules/advert_revert

like it says at the top of the file. Yes, of Course I use DarkRP, and the Server is currently using pretty much the latest Version of DarkRP (https://github.com/FPtje/DarkRP).

It still puts in a billboard if you do /advert message

Can you help me with that?