I'm thinking of smoking a joint in the guest bathroom?

Just got back home from college, and I got a few grams of weed from some friends before I left. I want to smoke it, but my mom is home. I don't want to leave the house because it's late, and if I tell her I'm going someplace at 10pm she might get suspicious. Also I don't have a pipe, or bong. All I have is zig zags for joint rolling. Some say you should smoke in the bathroom, but I'm not sure if it will leave a smell or not. Also, how long does the smell linger in the bathroom? It's the guest room so she usually only goes in it if she needs to clean it (it's on one side of the house, while her room is on the opposite side)