SERVER
------------
TITAN = TITAN or {}

function GM:AcceptStream( pl, handler, id )
    return true; // Allow all streams
end

function TITAN:OpenTestMenu( ply, handle, id, encoded, decoded )
        if(ply:IsAdmin() or ply:IsSuperAdmin()) then
                datastream.StreamToClients( ply, "OpenTestMenuRet", { ["bool"] = true } );
        end
end
datastream.Hook( "OpenTestMenu", TITAN:OpenTestMenu );
------------

CLIENT
------------
TITAN = TITAN or {}

function TITAN:OpenTestMenuRet( handle, id, encoded, decoded )
        if(decoded.bool == true) then
                local TITAN:testMenu = vgui.Create("DFrame")

                TITAN:testMenu:SetPos(100,100)
                TITAN:testMenu:SetSize(200,200)
                TITAN:testMenu:SetTitle("Test")
                TITAN:testMenu:MakePopup()
        else
                print("You do not have permission to open the test menu!")
        end
end
datastream.Hook( "OpenTestMenuRet", OpenTestMenuRet );

function TITAN:RequestOpenTestMenu( )
        datastream.StreamToServer( "OpenTestMenu", { } );
end
concommand.Add("TITAN_reqOpenTestMenu", TITAN:RequestOpenTestMenu)
------------