When player clicks on button, they need to change to the model in the Lighting
function Click(mouse)
script.Parent.Parent.Parent.Parent.Parent.CharacterAppearance = game.Lighting.Models.Crazy
script.Parent.Parent.Parent.Parent.Parent.Character:BreakJoints()
end
script.Parent.MouseButton1Down:connect(Click)

3 comments
Not really sure what you're going for here, could you elaborate more? Also, I'm pretty sure there are some rules about needing click detectors when determining if someone's mouse clicked on a brick. If you're checking it from the mouse's perspective this isn't necessary, but this is something from a server script.
First of all, indent your code. Second of all, elaborate on your question. Have you tested this, what is / isn't working, what are the outputs? I think you'll find changing a player to a model in lighting is more difficult than you think.
This is not a request site, but it's possible.