local plyr = game.Players.LocalPlayer
local button = script.TriggerButton.Value

function onClick(activator)
    if activator == plyr and not plyr.PlayerGui:FindFirstChild("FlashGUI") then
        button.FlashGUI:Clone().Parent = plyr.PlayerGui
    end
end

button.ClickDetector.MouseClick:Connect(onClick)


-- either change button to the path of the brick or, so you can move it around without worrying about changing your script, create an  -- ObjectValue as a child of the script and set its value to the brick with the picker tool and change its name to TriggerButton
-- as for the script, put it in game.StarterPlayer.StarterPlayerScripts