Pentagram on the front door, traps in the walkway, or even better, try to convert them to something absurd. Make up a religion and see if you can convert them, if they don't convert, scream to them that your "god" will strike them down to the hell's below. If they continue do not listen, then tell them you are going to war with then and pull out a foam sword and hit them.
My rant is I'm at work and bored.