If you see someone looking into your bathroom stall, this means that you are feeling very vulnerable. There is a lack of privacy in your life. Perhaps you are feeling very unhappy because of the fact that you lost your freedom, therefore you dream about bathroom stall.
Dream dictionary: bathroom stall dream meanings
The bathroom in dreams is known as the symbol of clean mind and soul, because it is the place where people take the shower, wash themselves and take care of their bodies. If the bathroom is clean and tidy, your mind and soul are as clean as the bathroom is. If the bathroom is very dirty or simply messy, you should look better after yourself. Perhaps you have too much stress and experiencing negative emotions. Make sure you get rid of it as soon as you can. If you are in the bathroom with someone else, it shows your desire to interact with this person better then you did before. To get more detailed dream interpretation please see the meaning of toilet and bathroom stall.