How to make Dialog pop up without a player clicking it?

Wait, I understand your question now. I thought you were talking about the dialog responses. So you're wanting to detect if the user makes the correct choice or not on the register?

To achieve this, you need to set up multiple events that will eventually be disconnected. You'd want to somehow communicate the correct response to the script. Once establishing the variables, this will prevent the script from erroring out. Now we will want the script to get the correct response. Let's just say when the user makes the right choice in the dialog box, the script will change a value in Workspace that will also provide the correct response.

Now I typed up the script before making this mini-tutorial, so try to follow along. You need to establish variables for what you will make events later on in the script. That way when you go to disconnect the events you will not receive an error. Whenever the CorrectResponse StringValue in Workspace is changed, the function will make new events and set them as the variables we set up. Whenever the user chooses a brick the script will execute the Check function which will determine if the correct response was chosen or not. If the correct response was chosen, then the specified brick will say "Thank you" and the function KillAll is called. KillAll is the function I created to kill all the events using the disconnect function. That way you can't just go, oh Pepperoni first then Cheese right after that.

local Pepperoni, Cheese, Sausage, Soda

function KillAll()
    Pepperoni:disconnect()
    Cheese:disconnect()
    Sausage:disconnect()
    Soda:disconnect()
end

function Check(Correct, Chosen)
    if Correct == Chosen then
        game:GetService('Chat'):Chat(game.Workspace.PartYouWantToShowThisMessageOn, "Thank you!")
        KillAll()
        --Fill in the rest.
    else
        game:GetService('Chat'):Chat(game.Workspace.PartYouWantToShowThisMessageOn, "I am never coming back!")
        KillAll()
    end
end

game.Workspace.CorrectResponse.Changed:connect(function(Correct) --Assume this is a StringValue in the Workspace.
    Pepperoni = game.Workspace.PepperoniOption.ClickDetector.MouseClick:connect(function()
        Check(Correct,"Pepperoni")
    end)
    Cheese = game.Workspace.CheeseOption.ClickDetector.MouseClick:connect(function()
        Check(Correct,"Cheese")
    end)
    Sausage = game.Workspace.SausageOption.ClickDetector.MouseClick:connect(function()
        Check(Correct,"Sausage")
    end)
    Soda = game.Workspace.SodaOption.ClickDetector.MouseClick:connect(function()
        Check(Correct,"Soda")
    end)
end)

######Hopefully this answered your question. I am sorry for the miscommunication beforehand. I did not completely understand your question to begin with. If you have any questions or you want further explanation on how this script works, just post in the comments below.