פירוש על עבודה זרה 94:4

The mishnah states that if his wall falls down, he should rebuild it four cubits within his own property. This way he is not building a wall for the shrine. But the problem is that this extra four cubits will now, de facto, become the property of the shrine.
The solution, the Talmud suggests (somewhat grotesquely) is that he use it to make a toilet. The idolatrous Temple will not get much benefit out of it. But then there is the problem of modesty. A person should not go to the bathroom where everyone can see him.
The Talmud offers two solutions. 1) The toilet will be for children, who do not need to be modest when they relieve themselves. 2) Instead of using the place for a toilet, he could put up a fence of thorns and shrubs. This will stop the idolatrous place from using that area and he will still not be providing a good wall for an idolatrous shrine.