Sometimes, as the weather gets colder, some of the neighborhood critters will enter our house uninvited and make their homes in the walls.  Usually these critters are just mice, so I use some traps with peanut butter to snap their furry little necks.  I really wouldn't have a problem with mice living in my house, but mice have a tendency to chew on things like wires, and I happen to like the wires in my house. 

This year, Wendy thought we had something larger than a mouse.  Sure enough, opening the attic door produced a firsthand view of a squirrel escaping through a hole it had chewed in one of the vents.  I angrily made some noise to drive away any stragglers, then nailed a piece of plywood over the vent.  The next day I went outside to make sure the plywood was still in place, and I saw the remnants of the plastic vent cover, scratched to pieces by a squirrel that likely came back to his warm attic home after a long day at the office, only to find that someone had boarded up his doorway, forcing him to totally freak out and try to break in.  But he failed.  Sure, I'll have to buy a new vent cover and some wood to cover up some holes, but that squirrel no longer lives in my house. 

I'm not a particularly violent person, but based on the amount of damage this squirrel caused, I considered buying a gun.  A pellet gun.  Because when you forcefully break into my house, expect a bullet in your hindquarters.