If you have a cat that likes to climb in the Christmas tree, there are several things you can do to discourage them. First, try placing some scented deterrents around the base of the tree. Cats are sensitive to smells, so they may be deterred from the area if they don't like the smell. You can also try hanging some tin foil or other shiny objects from the branches of the tree, as cats tend to be afraid of these objects. Additionally, make sure to keep the tree watered and healthy so that it doesn't drop needles or other debris that could entice the cat to play in it.