When my kids were young, I'd often come out of the bathroom to find everyone else who lived in the house (one husband, two daughters, and one cat) standing just outside the door waiting for me.
Nowadays, one of my two cats will nearly trip me, trying to race ahead and get into the bathroom before I do. The other one will follow but will often just sit down at the doorway, waiting to be "invited" in. If I just close the door in her face, she'll scratch at the doorjamb and then lie down and stick her paws underneath the door.