It is inconsiderate to monopolize a restroom
Tommy has to use the public restroom, but he doesn't like other people being in there at the same time as him.
Tommy wants to use the restroom alone.
Tommy waits until the restroom is empty and then goes inside.
Tommy enters the restroom and blocks the door so no one else can enter.
Tommy uses the restroom without worrying about anyone else being inside.
Tommy gets yelled at by other people from outside who want to enter.